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HYDRAULICS. 

WATER-WHEELS — WINDMILLS — SERVICE  PIPE — DRAINAGE,  ETC. 


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DU  BOIS. 


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HYDRAULICS  AND  HYDRAULIC  MOTORS. 

With  numerous  practical  examples  for  the  calculation  and 
construction  of  Water-wheels,  including  Breast,  Undershot, 
Back-pitch,  Overshot  Wheels,  etc.,  as  well  as  a  special  discus- 
sion of  the  various  forms  of  Turbines,  translated  from  the 
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HYDRAULICS. 

The  Flow  of  Water  through  Orifices,  over  Weirs,  and  through 
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WATER-WHEELS    OR    HYDRAULIC    MOTORS. 

Translated  from  the  French  Cours  de  Me'canique  Appliquee, 
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OPINIONS    OP    CHEMISTS    IN   REGARD  TO 

THE    USE    OP    LEAD  PIPE    FOR    SERVICE 

PIPE 

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THE    PRACTICE    OP     THE     IMPROVEMENT     OP 

THfi    NON-TIDAL  RIVERS  OP  THE  UNITED 

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—Major  P.  C.  HAINS,  Corps  of  Engineers,  U.S.A. 

A  HISTORY  OP  THE  MISSISSIPPI  JETTIES  AT 
THE  MOUTH  OP  THE  MISSISSIPPI  RIVER. 

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WATER    SUPPLY 


CONSIDERED    MAINLY    FROM    A 


CHEMICAL   AND    SANITARY   STANDPOINT. 


BY 

WM.   RIPLEY    NICHOLS, 

PROFESSOR   AT    THE   MASSACHUSETTS    INSTITUTE   OF   TECHNOLOGY. 


THIRD  EDITION. 


UNIVERSITY 


JOHN    WILEY    &    SONS 


COPYRIGHT,  1883, 
BY  W.  R.  NICHOLS. 


PREFACE, 


THE  following  pages  contain,  somewhat  amplified,  the  sub- 
stance  of  a  course  of  "  Lectures  on  Water  Supply  "  which  the 
author  has  been  in  the  habit  of  delivering  before  certain  classes 
at  the  Institute  of  Technology.  It  is  primarily  as  an  aid  to 
engineering  and  other  students  at  this  and  similar  institutions 
that  the  book  is  printed.  It  is  hoped,  however,  that  the  book 
will  be  found  of  service  to  young  engineers,  to  persons  in  charge 
of  water  works,  to  water  committees,  and  to  others  who  are 
interested  in  the  matter  of  water  supply. 

The  aim  is  not  to  present  a  complete  treatise  on  water  supply 
for  the  civil  engineer,  nor  a  treatise  on  water  analysis  for  the 
chemist,  nor  a  treatise  on  mycology  for  the  botanist,  and  certainly 
not  a  treatise  on  sanitary  science  for  the  physician,  but,  rather, 
to  occupy  a  territory  which  encroaches  on  the  fields  of  these  and 
other  professions  and  which  belongs  exclusively  to  no  one  alone 
— ground,  in  fact,  with  which  all  who  are  professionally  inter- 
ested in  water  supply  must  be  more  or  less  familiar. 

The  metric  system  of  weights  and  measures  is  used,  as  well  as 
the  English ;  tables  for  the  conversion  of  one  system  into  the 
other  will  be  found  at  the  end  of  the  volume.  In  the  nomen- 
clature of  chemical  substances,  the  old  and  more  familiar  terms 
are  generally — although  not  exclusively  employed — such  as  car- 
bonate of  soda  and  not  sodic  carbonate,  sulphate  of  lime  rather 
than  sulphate  of  calcium. 

The  author  has  quoted  freely  from  other  works  on  the  sub- 
ject, and  from  his  own  earlier  reports,  now  mostly  out  of  print. 


iv  PREFACE. 

He  would  acknowledge  especial  indebtedness  to  the  Reports  of 
the  Rivers  Pollution  Commission,  and  to  Fischer's  chemische 
Technologic  des  Wassers,  and  regrets  that  Wolffhtigels  Wasser- 
versorgung  did  not  come  to  hand  until  the  manuscript  was  in 
the  hands  of  the  printer. 

MASSACHUSETTS  INSTITUTE  OF  TECHNOLOGY, 
Boston,  Mass.,  May,  1883. 


TABLE    OF   CONTENTS. 


PAGES 

INTRODUCTORY  CHAPTER. — SOLUTION i-  16 

Solution  of  solid  substances. — Saturated  and  supersaturated  solu- 
tions.— Condition  of  mixed  solutions. — Various  means  of  hastening 
solution. — Effects  of  dissolved  solids. — Solution  of  gases. — Supersat- 
urated solutions  of  gases. — Facilitating  gaseous  solution. — Solubility 
of  liquids  in  water. — Distinction  between  solution  and  suspension. 

CHAPTER  I. — DRINKING  WATER  AND  DISEASE 17-28 

CHAPTER  II. — WATER  ANALYSIS 29-  47 

Suspended  matter. — Dissolved  gases. — Total  solids  in  solution. — 
Chlorine. — Hardness. — Combined  nitrogen. — Organic  matter. — 
Standards  of  purity. — Popular  tests. — Collection  of  samples. 

CHAPTER  III. — RAIN  WATER  AS  A  SOURCE  OF  SUPPLY.    48-  55 

Examination  of  cistern  water. — Natural  and  artificial  ice. — Chemical 
examination  of  ice. 

CHAPTER  IV. — SURFACE  WATERS  AS  SOURCES  OF  SUP- 
PLY      56-  78 

Turbidity  of  streams.  —Pollution  of  streams. — Self-purification  of 
streams. — Oxidation. — Deposition. — Dilution. — Prevention  of  pollu- 
tion. 

CHAPTER  V. — SURFACE  WATERS  AS  SOURCES  OF  SUP- 
PLY (continued?) 79-104 

Animal  and  vegetable  life. — Odors  and  tastes. — Temperature. — Ex- 
amination of  surface  waters. — Variation  of  surface  waters. 

CHAPTER  VI.— GROUND  WATER  AS  A  SOURCE  OF  SUP- 
PLY    105-132 

Methods  of  utilizing  ground  water. — Effects  of  pumping  on  ground 
water. — Driven  wells. — Natural  filtration. — Examination  of  ground 
water. — Pollution  of  domestic  wells. — Examination  of  wells. 


VI  TABLE   OF   CONTENTS. 

CHAPTER  VII. — DEEP  SEATED  WATER  AS  A  SOURCE 
OF  SUPPLY 133-145 

Artesian  wells. — Deep  wells. — Characteristics  and  examination  of 
deep  seated  water. 

CHAPTER  VIII. — ARTIFICIAL  IMPROVEMENT  OF  NATU- 
RAL WATER 146-180 

Sedimentation. — Storage.  —  Aeration.  —  Filtration.  —  Principles  of 
sand  filtration. — Practical  results  of  artificial  filtration. — Sand  filtra- 
tion in  the  United  States. — Advantages  of  covered  filter  beds. — Ex- 
pense.— Other  filtering  materials. — Household  filtration. 

CHAPTER  IX. — ARTIFICIAL  IMPROVEMENT  OF  NATU- 
RAL WATER  (continued) 181-193 

Softening  of  hard  water. — Temporary  hardness. — Permanent  hard- 
ness.— Chemical  processes. — Distillation. 

CHAPTER  X. — SOME  GENERAL  CONSIDERATIONS 194-215 

Quantity  and  waste. — Conduits  and  distribution  pipes. — Service 
pipes. 

BIBLIOGRAPHY 216-220 

TABLES  FOR  CALCULATIONS 221-225 


INTRODUCTORY    CHAPTER. 


SOLUTION. 


No  water  which  occurs  in  nature  is  pure  in  the  strict  chem- 
ical sense  of  the  term,  but  all  natural  waters,  however  free  from 
suspended  particles  of  foreign  matter  which  are  visible  to  the 
eye,  invariably  contain  in  solution  more  or  less  of  substances 
which,  in  their  ordinary  condition,  are  solids  or  gases.  It  is 
therefore  important,  in  the  beginning,  to  understand  some  of 
the  many  things  which  might  be  said  of  solution  in  general. 

Solution  of  Solid  Substances. 

If  some  pure  salt  be  put  into  water,  after  a  time  the  salt  dis- 
appears from  sight,  and  becomes  incorporated  with  the  water,  so 
that  it  is  no  longer  possible  to  distinguish  it  by  the  eye,  or  to 
remove  it  by  ever  so  fine  a  filter.  As  far  as  we  can  make  it  out, 
the  change  that  has  taken  place  is  as  follows  :  The  ultimate  par- 
ticles of  the  salt  (the  molecules  of  the  chemist)  are  no  longer 
held  together  in  a  solid  mass  by  that  mutual  attraction  which  we 
call  cohesion,  but  have  become  separated  from  each  other  and 
distributed  among  the  particles  (molecules)  of  the  water  so  as  to 
form  a  homogeneous  mixture.  As  far  as  we  can  perceive,  it  is, 
indeed,  simply  a  mixture — a  mixture  of  particles  of  salt  with 
particles  of  water — we  can  discover  no  chemical  change,  we  can 
trace  no  chemical  action  between  the  dissimilar  substances,  salt 
and  water.  This  is  an  example  of  what  is  usually  called  physical 
solution.  The  solution  differs,  of  course,  essentially  from  the 
water.  The  transparency  is  not  noticeably  impaired,*  but  if 

*  This  would  not  be  true  if,  instead  of  common  salt,  we  had  taken  a  strongly 
colored  substance  like  the  permanganate  of  potash.  In  such  a  case  the  strong  color 
of  the  solution  would  perceptibly  diminish  its  transparency  ;  otherwise  the  phenom- 
ena would  be  as  above. 


2  INTRODUCTORY   CHAPTER. 

much  salt  has  been  used  the  mobility  of  the  water  has  been 
lessened,  the  boiling  point  has  been  raised,  the  freezing  point 
and  the  temperature  of  maximum  density  have  been  lowered, 
the  specific  gravity,  the  specific  heat  and  the  electrical  resistance 
have  also  been  changed.  If,  now,  the  solution  be  allowed  to 
evaporate  at  the  ordinary  temperature,  or  if  the  evaporation  be 
hastened  by  artificially  raising  the  temperature,  the  water  passes 
off  as  vapor  and  the  salt  is  recovered  unchanged. 

If  a  strip  of  zinc  be  immersed  in  ordinary  muriatic  (hydro- 
chloric) acid  somewhat  diluted,  the  zinc  gradually  disappears, 
but  at  the  same  time  there  is  a  marked  effervescence,  due  to  the 
escape  of  hydrogen  gas,  as  well  as  a  considerable  increase  of 
temperature.  There  is,  in  fact,  evidence  enough  that  chemical 
change  is  taking  place.  When  the  action  is  over,  we  have  a 
transparent  liquid  which  is  sometimes  spoken  of  as  a  "  solution 
of  zinc,"  and  the  phenomenon  is  spoken  of  as  chemical  solution. 
If,  however,  we  study  the  action  that  occurs,  we  find  that  it  may 
be  regarded  as  taking  place  in  two  steps :  in  the  first  place,  the 
zinc  acts  on  the  acid  to  set  free  hydrogen  gas,  and  to  form  a  new 
compound,  chloride  of  zinc ;  in  the  second  place,  the  chloride  of 
zinc  thus  formed  dissolves  in  the  liquid  present,  as  did  the  salt  in 
the  previous  example. 

Using  the  term  solution  in  its  ordinary  sense,  to  cover  all 
cases  of  the  disappearance  of  a  solid  *  in  a  liquid,  there  are  many 
cases  which  can  be  assigned  without  hesitation  to  one  or  the 
other  of  the  two  classes  of  actions  just  described,  but  it  is  by  no 
means  easy  in  all  cases  to  say  whether  we  are  dealing  with  a 
simple  (physical)  solution,  or  whether  chemical  action  also  takes 
place.  Thus,  if  dry  oxide  of  sodium  be  put  into  water,  it  dis- 
solves, that  is,  the  solid  disappears,  but  we  are  quite  sure  in  this 
case  that  it  is  not  the  oxide  of  sodium  which  exists  in  the  solu- 
tion ;  in  fact,  the  oxide  of  sodium  combines  chemically  with  a 
portion  of  the  water  to  form  hydrate  of  sodium,f  and  it  is  this 
hydrate,  and  not  the  oxide,  which  actually  dissolves  in  the  mass 
of  the  water  present.  Again,  if  dry  carbonate  of  soda  be  put 
into  water,  there  is  next  to  no  doubt  that  it  combines  with  a 

*  The  solution  of  gases  and  liquids  will  be  considered  further  on. 
f  The  chemical  change  which  takes  place  is  thus  symbolized :   NaaO  +  HaO  = 
2NaOH. 


SOLUTION   OF   SOLID   SUBSTANCES.  3 

portion  of  the  water,  and  that  the  compound  which  actually 
enters  into  solution  has  the  same  composition  as  the  crystallized 
carbonate  which  contains,  in  addition  to  the  elements  of  carbonate 
of  soda,  also  a  quantity  of  water.  With  regard  to  many  solids, 
we  are  in  doubt  whether  they  dissolve  simply  as  such,  or  first 
undergo  chemical  change.  In  cases  like  that  of  common  salt, 
first  mentioned,  we  can  trace  no  such  chemical  change,  but  it  is 
by  no  means  certain  that  no  chemical  action  takes  place,  and 
many  regard  the  solution  of  salt  and  other  similar  substances  as 
due  to  the  same  cause  as  that  to  which  chemical  action  in  gen- 
eral is  due,  manifested,  however,  to  a  slight  degree.'" 

The  term  solution  is  applied  almost  exclusively  to  cases  where 
the  dissolving  substance,  the  solvent,  is  a  liquid  ;  the  substance 
dissolved  may  be  solid,  liquid,  or  gaseous.  Every  liquid  can  act 
as  a  solvent  for  certain  things,  although,  if  the  liquid  is  of  a 
marked  alkaline  or  acid  character,  solution  is  usually  accompanied 
by  chemical  change.  Water  is  spoken  of  as  the  universal  sol- 
vent, and  more  than  any  other  liquid  does  it  dissolve  various 
substances  without  evident  change.  In  what  follows,  we  shall 
use  the  terms  soluble  and  insoluble  to  mean  soluble  and  insoluble 
in  water. 

Solids  differ  from  each  other  very  much  in  the  facility  with 
which  they  may  be  dissolved  in  water ;  thus,  chloride  of  calcium, 
if  merely  left  exposed  to  the  air,  readily  absorbs  from  the  atmos- 
phere enough  water  to  dissolve  it,  and  is  an  example  of  a  so- 
called  deliquescent  substance  ;  on  the  other  hand,  sulphate  of  lead 
requires  about  23,000  times  its  own  weight  of  water  (Fresenius), 
and  quartz  may  be  said  to  be  insoluble.  At  a  given  temperature 
a  certain  quantity  of  water  will  always  dissolve  the  same  weight 
of  a  particular  substance,  and,  as  a  general  rule,  the  amount 
which  can  be  dissolved  increases  with  increase  of  temperature. 
The  effect  of  increased  temperature,  however,  differs  greatly  with 
different  substances.  Thus  chloride  of  sodium  (common  salt)  is 
more  soluble  in  hot  than  in  cold  water,  but  only  very  slightly 
so ;  in  the  case  of  chloride  of  potassium,  however,  the  amount 
dissolved  increases  regularly  with  the  temperature,  while  in  the 
case  of  nitrate  of  potassium  the  increase  of  solubility  for  a 

*  See,  for  instance,   a  paper  On   Solution   and  the  Chemical   Process.     Hunt's 
Chemical  and  Geological  Essays,  pp.  448  and  foil. 


INTRODUCTORY   CHAPTER. 


FlG.  I.— CURVES   OF  SOLUBILITY. 


given  increase  of  temperature  is  greater  the  higher  the  tempera- 


ture : 


ioo  grams  of  water  at    o°  C.  dissolve  of  chloride  of  potassium. 

20° 

40° 

6oD 
ioo  grams  of  water  at    o°  dissolve  of  nitrate  of  potassium 

20° 

40° 

60° 


29-23  L 

34-70  , 
40.18  [ 

45-66  f 

13-32  j. 

31-70  ! 

63  97  [ 
uo-33  f 


EIFF.  FOR 
10°. 

5-47 

5-48 
5-48 

18.38 
32  C7 
46.36 


SOLUTION   OF   SOLID    SUBSTANCES. 


The  diagram  on  the  opposite  page  shows  the  relation  of  solu- 
bility to  temperature  in  the  case  of  a  number  of  common  salts. 
The  horizontal  lines  indicate  the  number  of  parts  by  weight  of 
the  salt  which  100  parts  by  weight  of  water  will  dissolve  at  the 
indicated  temperature. 

There  are  some  remarkable  exceptions  to  the  general  rule 
that  a  larger  amount  of  a  substance  can  be  dissolved  in  a  given 
quantity  of  hot  water  than  in  the  same  quantity  of  water  at  a 
lower  temperature.  Sulphate  of  lime  is  one  of  these  exceptions. 
This  substance  occurs  in  sea-water  and  in  other  natural  waters, 
and,  by  virtue  of  the  fact  that  its  solubility  decreases  with 
increase  of  temperature,  it  gives  much  trouble  in  steam-boilers 
by  separating  out  from  the  water  and  forming  a  coherent  scale. 
The  following  table  shows  the  solubility  of  sulphate  of  lime  in 
sea-water  at  temperatures  above  103°  Centigrade. 

TABLE  I. — SOLUBILITY  OF  SULPHATE  OF  LIME  IN  SEA-WATER.* 


SEA-WATER  SATURATED  WITH  SULPHATE  OF 

TEMPERATURE  IN  DEGREES 

LIME 

Centigrade. 

Fahrenheit. 

PRESSURE  IN 
ATMOSPHERES. 

Marks  (at  15° 
C.)on  Beaume"'s 
hydrometer. 

Or  has  a  specific 
gravity  of 

Contains  per 
cent  of  sulphate 
of  lime. 

103. 

217.4 

12°.  5 

1.090 

0.500 

103.80 

218.8 

12° 

.085 

0.477 

105.15 

221.3 

11° 

.078 

0.432 

108.60 

227.5 

-25 

10° 

070 

0-395 

I  I  I  .  00 

231.8 

•25 

9° 

-063 

0-355 

113.20 

235-3 

•25 

8° 

.056 

0.310 

115.80 

240.4 

•50 

7° 

048 

0.267 

118.50 

245-3 

•50 

6° 

.041 

0.226 

121.20 

250.2 

50 

5° 

•034 

0.183 

124. 

255-2 

2. 

4° 

027 

0.140 

127.90 

262.2 

2. 

3' 

.020 

0.097 

130. 

266.0 

2.50 

2° 

.0*3 

o  c6o 

133.30 

271.9 

2.50 

1° 

.007 

0.023 

This  table  shows  that  when  sea-water  is  boiled  under  a  press- 
ure of  one  atmosphere,  or  at  a  temperature  of  103°  C.,  it  will 
become  saturated  with  sulphate  of  lime,  when,  by  evaporation, 
its  density  has  been  elevated  to  I2°.5  Beaume,  and  it  will  then 
contain  0.5  per  cent  of  the  sulphate;  at  1.25  atmospheres,  or 
io8°.6  C.,  the  water  will  be  saturated  with  sulphate  when  it 

*  Couste  :  Annales  des  Mines,  v  (1854),  p.  80.     The  second  and  fifth   columns 
have  been  added  to  Couste's  table. 


6  INTRODUCTORY  CHAPTER. 

marks  10°  B.,  and  will  then  contain  0.395  per  cent  of  the  sul- 
phate. At  a  pressure  of  two  atmospheres,  that  is,  at  a  tempera- 
ture of  about  125°  C.,  sea-water,  in  its  natural  state  and  without 
having  undergone  any  concentration,  is  very  near  the  point  at 
which  saturation  occurs,  for  the  density  of  sea-water  is  from  3° 
to  3°. 5  B.,  and  this,  according  to  the  table,  would  correspond  to 
a  temperature  of  about  125°  C.  Sulphate  of  lime  becomes  com- 
pletely insoluble,  either  in  fresh  or  sea-water,  at  temperatures 
between  140°  C.  and  150°  C.  (284°-3O2°  F.). 

Saturated  and  supersaturated  solutions. — At  any  particular 
temperature  a  solvent  can  take  up  a  definite  amount  of  a  sub- 
stance soluble  in  it,  and  no  more.  The  solution  is  said  to  be 
saturated  when  it  contains  as  much  of  the  dissolved  substance  as 
can  be  taken  up  at  the  given  temperature.  It  is,  however,  often 
possible  to  prepare  what  are  called  supersaturated  solutions,  by 
making  a  saturated  solution  at  some  higher  temperature  and 
allowing  the  liquid  to  cool.  Suppose,  for  example,  that  a  satu- 
rated solution  of  nitrate  of  potassium  was  made  at  60°  using 
loo  c.c.  of  water;  according  to  the  diagram  on  page  4,  at  that 
temperature  100  grams  of  water  would  dissolve  110.33  grams  of 
the  salt.  If,  now,  the  solution  were  cooled  to  20°,  we  should 
expect  that  there  would  then  remain  dissolved  31 .70  grams,  and 
that  78.63  grams  would  separate  in  the  solid  condition  during 
the  cooling;  in  this  particular  case,  the  expectation  would  be 
approximately  realized  ;  but,  with  many  salts,  if  a  saturated  solu- 
tion be  cooled  quietly  without  agitation,  it  happens  that,  when 
cold,  the  liquid  still  retains  more  of  the  salt  than  it  could  take  up 
at  the  lower  temperature.  In  fact,  Storer  says:*  "It  is  often 
exceedingly  difficult  thus  to  obtain  normally  saturated  solutions, 
even  of  our  most  common  and  easily  crystallized  salts,  within  the 
limits  of  time  which  can  be  conveniently  allotted  to  a  single 
experiment." 

In  the  case  of  some  particular  salts  the  phenomenon  of  super- 
saturation  is  very  marked.  Thus,  at  a  temperature  of  33°  C., 
water  will  dissolve  about  half  its  own  weight  of  Glauber's  salt 
(hydrated  sulphate  of  sodium),  and  if  the  solution  be  protected 
from  dust  and  allowed  to  cool  quietly  to  the  ordinary  tempera- 
ture, the  whole  of  the  compound  remains  in  solution.  If,  now, 

*  Dictionary  of  Solubilities,  Preface. 


SOLUTION   OF   SOLID   SUBSTANCES.  7 

a  small  crystal  of  the  same  kind  as  the  original  salt  be  dropped 
into  the  solution,  about  three-fifths  of  the  salt  separates  out  in 
the  crystalline  form,  and  the  whole  mass  becomes  nearly  solid. 

Condition  of  mixed  solutions. — Natural  waters  usually  contain 
a  variety  of  foreign  substances,  and  it  is  worth  while,  at  this 
point,  to  inquire  into  the  condition  of  things  which  exist  in  a 
dilute  solution  containing  at  the  same  time  several  different  salts. 
We  will  first  take  a  simple  case  where  chemical  analysis  shows 
the  existence  of,  say  a  chloride  and  a  sulphate,  and  of  potassium 
and  sodium.  The  question  may  be  asked,  whether  the  solution 
contains  chloride  of  sodium  and  sulphate  of  potassium,  or  sul- 
phate of  sodium  and  chloride  of  potassium,  or  whether  all  four 
of  these  compounds  exist  at  the  same  time.  Now,  while  the 
latter  is  believed  to  be  the  true  state  of  the  case,  chemical 
analysis  is  powerless  to  answer  the  question,  and  two  solutions 
undistinguishable  from  each  other  could  be  prepared  by  taking 
each  pair  of  salts  indicated  above  in  the  right  proportion.*  If  a 
number  of  soluble  salts  are  mixed  together  in  solution,  the  matter 
becomes  more  complicated,  but  in  stating  the  results  of  analysis, 
certain  conventional  forms  of  statement  are  adopted.  Thus  we 
might  mix  together  in  dilute  solution  and  in  the  right  proportion, 
sulphate  of  sodium  and  chloride  of  calcium,  but  if  the  solution 
were  analyzed,  it  would  be  reported  as  containing  sulphate  of 
calcium  and  chloride  of  sodium,  for  the  reason  that  the  sulphate 
of  calcium  is  much  less  readily  soluble  in  water  than  the  other 
compounds,  and  if  the  solution  in  question  were  gradually  con- 
centrated by  evaporation,  the  sulphate  of  calcium  would  separate 
in  the  solid  form  ;  if  the  evaporation  were  carried  to  dryness,  the 
sulphate  of  calcium  and  chloride  of  sodium  would  remain,  each 
crystallized  by  itself.  For  this  reason  chloride  of  calcium  would 
never  be  represented  as  existing  in  the  presence  of  sulphate  of 
sodium,  although,  in  a  dilute  solution,  it  is  probable  that  a  por- 
tion of  the  calcium  would  actually  exist  in  the  form  of  chloride. 
It  should  be  said  that  much  difference  of  opinion  and  practice 
exists  with  reference  to  the  best  way  to  represent  the  constit- 
uents of  a  mixed  solution,  and  two  chemists  will  often  report 

*  We  are  not  in  absolute  ignorance  as  to  the  laws  which  govern  the  partition  of  a 
base  among  different  acids,  or  of  an  acid  among  different  bases,  or,  indeed,  of  the  acid 
and  basic  radicals  among  different  salts.  Our  knowledge,  however,  is  too  limited  to  be 
applied  practically  to  any  considerable  extent  in  such  a  case  as  that  of  a  natural  water. 


INTRODUCTORY  CHAPTER. 


very  different  statements  of  the  analysis  of  the  same  solution, 
while  the  numerical  results  actually  obtained  are  the  same. 

The  following  statement  of  the  analysis  of  Croton  water,  by 
Professor  Chandler,  is  an  example  of  the  form  in  which  such 
reports  are  usually  made  : 

SOLIDS  CONTAINED  IN  ONE  GALLON  OF  CROTON  WATER. 


SUMMER,  1869. 
Grains. 

MAY  ii,  1872. 
Grains. 

0.402 

o  284. 

Sulphate  of  Potash  

O    I7Q 

O   2O^ 

Sulphate  of  Soda  

0.260 

O  O24. 

o.izS 

O.O24. 

Bicarbonate  of  Lime  . 

2    67O 

2    111 

Bicarbonate  of  Magnesia  

I.  QI7 

I    Il8 

Silica  

J     •* 

O.62I 

O.222 

Alumina  and  Oxide  of  Iron  

a  trace 

o  058 

0.670 

o  874. 

Total 

6  87-* 

5^60 

The  following  statement  represents  the  actual  results  of  an- 
alysis, from  which  the  previous  statement  was  made  up  accord- 
ing to  the  conventional  plan  usually  adopted  : 

SOLIDS  CONTAINED  IN  ONE  GALLON  OF  CROTON  WATER. 


SUMMER,  1869. 
Grains. 

MAY  ii,  1872. 
Grains. 

Soda  

o  126 

O   1^7 

Potash  

O   OQ7 

O.  IOQ 

Lime  

o  988 

o  819 

O    524. 

o  160 

O.  241 

O    172 

Sulphuric  Acid  .    . 

O   122 

o  124 

o  621 

O  222 

a  trace 

O.O^S 

Carbonic  Acid  (calculated)  .  . 

2   604 

2   O74 

O    m2 

O   421 

Organic  and  Volatile  Matter                      .  . 

o  670 

O   874. 

Less  Oxygen  equivalent  to  the  Chlorine  ...           . 

6.927 

O   O^4 

5-399 

O   O1Q 

Total  

6  873 

5  .  l6o 

Effect  of  the  presence  of  one  substance  on  the  solubility  of  another 
substance. — When  water  has  dissolved  as  much  of  a  given  sub- 
stance as  it  can  under  the  existing  conditions,  it  is  still  able  to 
take  up  more  or  less  of  a  second  substance.  In  general,  the 


SOLUTION   OF   SOLID    SUBSTANCES.  9 

presence  of  one  substance  in  a  solution  will  modify  the  action  of 
the  liquid  on  another  substance  presented  to  it;  thus,  while 
cyanide  of  silver  is  insoluble  in  water,  it  dissolves  readily  in  an 
aqueous  solution  of  cyanide  of  potassium.  Again,  although  car- 
bonate of  lime  dissolves  only  to  a  very  slight  extent  in  pure 
water,  it  dissolves  to  a  considerable  extent  in  water  containing 
carbonic  acid,  and  is  a  frequent  constituent  of  natural  waters. 
When  such  waters  are  boiled,  the  carbonic  acid  escapes,  and  as 
the  water  is  no  longer  able  to  keep  the  carbonate  of  lime  in  solu- 
tion, this  compound  separates  out  and  is  one  of  the  substances 
which  cause  trouble  in  steam  boilers  by  forming  an  incrustation 
or  scale.  Undoubtedly,  in  such  cases  as  those  mentioned,  chem- 
ical action  takes  place  to  a  greater  or  less  extent  between  the 
substances  dissolved. 

Various  means  of  hastening  solution. — The  solution  of  a  solid 
substance  is  facilitated  by  any  means  which  tends  to  bring  con- 
tinually fresh  portions  of  the  solvent  into  intimate  contact  with 
the  substance  to  be  dissolved.  It  is  consequently  of  advantage 
to  reduce  the  solid  to  a  fine  powder,  and  to  agitate  the  mixture. 
Where  there  is  no  objection  to  heating  the  liquid,  the  solution  is 
facilitated  by  so  doing.  Advantage  may  be  taken  of  the  fact 
that  the  solution  has  a  greater  specific  gravity  than  the  solvent, 
by  suspending  the  solid  near  the  sur- 
face of  the  liquid.  This  may  be 
easily  shown  by  putting  crystals  of 
some  colored  salt,  as  bichromate  of 
potash  or  sulphate  of  copper,  into  a 
cone  of  wire  gauze,  or  into  a  funnel, 
or  into  a  tube  over  one  end  of  which 
a  piece  of  cloth  is  tied,  and  suspend- 
ing the  apparatus  in  a  vessel  of  water. 
The  solution,  as  it  is  formed,  falls 
toward  the  bottom  of  the  vessel, 
marking  its  path  through  the  water  FlG* 

by  colored  threads,  and  this  action  continues  until  the  solution  is 
saturated. 

In  preparing  brine  or  a  solution  of  copperas— as  a  disinfectant, 
for  instance — much  time  may  be  saved  by  suspending  the  salt  or 
the  copperas  in  a  basket  or  coarse  bag  near  the  top  of  the  tub  or 
barrel  in  which  the  solution  is  made,  instead  of  putting  the  solid 


IO  INTRODUCTORY   CHAPTER. 

at  the  bottom  of  the  water  and  endeavoring  to  hasten  solution 
by  stirring. 

Effect  of  dissolved  solids  on  various  physical  phenomena. — The 
effect  of  dissolved  solid  substances  is  to  increase  the  specific 
gravity,  and  in  the  case  of  many  substances  tables  have  been 
prepared  from  which  the  percentage  of  the  substance  dissolved 
can  be  learned  by  observing  the  specific  gravity  of  the  solution. 
Similar  tables  have  also  been  prepared  for  solutions  of  gases  and 
liquids. 

The  presence  of  dissolved  substances  raises  the  boiling  point 
of  the  solution,  and  the  stronger  the  solution,  the  higher  the 
boiling  point.  Thus,  ordinary  sea-water  boils  at  about  101°  C. 
(2 1 3°. 8  F.),  while  a  saturated  solution  of  acetate  of  potash  does 
not  boil  until  the  temperature  reaches  169°  C.  (304°.  2  F.). 

The  effect  of  dissolved  solids  is  to  lower  the  freezing  point 
and  the  temperature  of  maximum  density.  Thus,  while  pure 
water  is  at  its  maximum  density  at  4°  C.  (39°.  2  F.),  and  freezes 
at  oc  C.  (32°  F.),  sea-water,  according  to  Despretz,  acquires  its 
maximum  density  at  3°. 67  C.  (38°. 6  F.),  and  freezes  at  -i°.88C. 
(28°. 6  F.). 

Solution  of  Gases. 

It  is  true  of  gases  as  of  solids  that  they  vary  very  much  in 
their  deportment  toward  water,  some  being  absorbed  by  it  with 
very  great  readiness,  while  others  may  be  kept  in  contact  with  it 
for  a  long  time  without  suffering  any  considerable  decrease  of 
bulk.  It  is  generally  true,  however,  of  gases,  that  they  dissolve 
to  a  certain,  even  if  to  a  slight,  extent,  and  the  amount  is  fixed 
and  definite  under  the  same  conditions  of  temperature  and  press- 
ure. As  a  rule,  increase  of  temperature  decreases  the  solubility, 
and  by  prolonged  boiling,  water  may  be  freed  from  the  gases 
which  it  holds  in  solution.*  The  specific  gravity  of  solutions  of 
gases  is  sometimes  lower  and  sometimes  higher  than  that  of  water. 

The  volume  of  a  gas  (expressed  in  cubic  centimeters  and 
measured  at  o°  C.,  and  under  a  pressure  of  760  m.m.  of  mercury) 
which  one  cubic  centimeter  of  water  will  dissolve  at  a  certain 

*  This  is  not  invariably  true.  Thus,  a  strong  solution  of  chlorhydric  acid  gas, 
when  heated,  gives  off  the  gas  until  the  amount  of  acid  in  the  remaining  solution  has 
been  reduced  to  20 . 24  per  cent  by  weight ;  the  solution  of  this  strength  distills 
unchanged  at  110°  C. 


SOLUTION   OF   GASES. 


II 


temperature,  is  called  the  coefficient  of  absorption  at  that  tem- 
perature. The  accompanying  table  gives  the  coefficient  of  absorp- 
tion at  various  temperatures  for  oxygen,  nitrogen,  carbonic  acid, 
and  ammonia.* 

TABLE  II. — COEFFICIENT  OF  ABSORPTION  OF  VARIOUS  GASES. 


TEMPERATURE. 

OXYGEN. 

NITROGEN. 

CARBONIC  ACID. 

AMMONIA. 

o°C. 

0.04114 

0.02035 

.7967 

1049  .  6 

i 

0.04007 

0.01981 

.7207 

1020.8 

2 

0.03907 

0.01932 

.6481 

993-3 

3 

0.03810 

0.01884 

•5787 

967.0 

4 

0.03717 

0.01838 

.5126 

941.9 

5 

0.03628 

0.01794 

•4497 

917.9 

6 

0.03544 

0.01752 

.3901 

895.0 

7 

0.03465 

0.01713 

•3339 

873-1 

8 

0.03389 

0.01675 

.2809 

852.1 

9 

0.03317 

0.01640 

.2311 

832.0 

10 

0.03250 

0.01607 

.1847 

812.8 

n 

0.03189 

0.01577 

.1416 

794-3 

12 

0.03133 

0.01549 

.1018 

776.3 

13 

0.03082 

0.01523 

•0653 

759  -6 

14 

0.03034 

0.01500 

.0321 

743-1 

15 

0.02989 

o  01478 

I.OO2O 

727.2 

16 

0.02949 

0.01458 

0-9753 

711.8 

17 

0.02914 

0.01441 

0.9519 

696.9 

18 

0.02884 

0.01426 

0.9318 

682.3 

19 

0.02858 

0.01413 

0.9150 

668.0 

20 

0.02838 

0.01403 

0.9014 

654.0 

From  the  table  it  is  seen  that  the  coefficient  of  carbonic  acid 
is  considerably,  and  that  of  ammonia  enormously,  greater  than 
that  of  oxygen  and  nitrogen.  In  the  case  of  gases  like  ammonia, 
hydrochloric  acid,  etc.,  we  have  no  difficulty  in  believing  that  the 
great  absorption  is  due  to  the  fact  that  chemical  combination 
takes  place,  and  this  is  probably  true  also  of  carbonic  acid,  sul- 
phuretted hydrogen,  etc.  It  is  a  curious  fact  that,  with  hydrogen, 
the  coefficient  of  absorption  in  water  is  the  same  at  all  tempera- 
tures from  o°  to  20°  C. 

If  the  pressure  be  increased,  a  greater  weight  of  the  gas  is 
dissolved  at  a  given  temperature,  and  the  increase  is,  in  fact, 
proportional  to  the  increase  of  pressure,  but  since  the  increased 
pressure  diminishes  the  volume  of  the  gas  in  the  same  propor- 
tion, the  same  actual  volume  of  gas  is  dissolved  whatever  the 
pressure.  In  the  case  of  gases  which  are  easily  liquefied  by  press- 
ure, or  of  those  which  are  very  soluble  in  water,  this  law  does 
not  hold  good  under  all  circumstances.  Thus  carbonic  acid  fol- 


*  Bunsen  :  Gasometrische  Methoden,  Braunschweig,  1877. 


12  INTRODUCTORY   CHAPTER. 

lows  the  law  only  when  the  pressure  is  small,  and  ammonia  gas 
only  at  high  temperature.  The  law  is,  in  general,  true  also  when 
water  is  exposed  to  an  atmosphere  of  mixed  gases ;  that  is,  each 
of  the  gases  in  the  mixture  is  dissolved  according  to  its  own 
coefficient  of  solubility ;  but  in  determining  the  actual  quantity 
of  any  one  gas  dissolved  (/.  e.,  the  volume  at  o°  and  760  m.m.),  it 
must  be  remembered  that  the  pressure  exerted  by  the  mixed 
gases  is  made  up  of  the  partial  pressures  of  the  several  gases  in 
the  mixture.  Thus,  whether  water  at  o°  C.  be  exposed  to  pure 
oxygen  with  a  pressure  of  760  m.m.,  or  to  air  at  the  pressure  of 
760  m.m.,  the  same  volume  of  oxygen  will  be  dissolved  in  either 
case,  namely,  as  we  see  from  the  table,  0.04114  c.c.  of  oxygen  in 
each  cubic  centimeter  of  water ;  but  in  the  one  case  we  have 
0.04114  c.c.  of  oxygen  with  a  pressure  of  760  m.m.,  whereas  in 
the  other  case  we  have  0.04114  c.c.  of  oxygen  with  a  pressure  of 
one-fifth  of  760  m.m.,  for  in  the  air  the  oxygen  forms  only  about 
one-fifth  part  by  volume.  It  follows  that  the  actual  quantity  of 
gas  (i.  e.,  the  volume  which  it  would  have  at  o°  and  760  m.m.)  in 
the  first  case  is  about  five  times  as  great  as  in  the  second.  It  is 
possible,  knowing  the  composition  of  the  mixture  of  dissolved 
gases  in  any  case,  to  calculate  the  composition  of  the  atmosphere 
to  which  the  water  was  exposed,  but  this  does  not  hold  in  the 
case  of  a  gas  forming  only  a  very  small  part  of  a  mixture. 
Owing  to  the  fact  that  the  coefficient  of  absorption  for  oxygen  is 
greater  than  that  of  nitrogen,  water  which  has  been  exposed  to 
ordinary  air  contains  these  two  gases  in  quite  a  different  propor- 
tion from  that  in  which  they  exist  in  the  air,  and  this  is  one  of 
the  proofs  adduced  to  show  that  in  the  air  the  gases  were  simply 
mixed  together,  and  not  chemically  combined.  The  relation  is 
as  follows : 

Composition  of  Air         Composition  of  "  Dissolved 
by  Volume.  Air"  by  Volume.* 

Oxygen 20.96  34-91 

Nitrogen 79-Q4  65 .09 

100.00  100.00 

Supersaturated  solutions  of  gases. — As  in  the  case  of  solids,  it 
is  possibly  to  prepare  temporarily  supersaturated  solutions  of 
gases.  Thus,  if  ordinary  "  soda-water  "  be  drawn  from  a  siphon 
or  from  a  fountain,  a  quantity  of  gas  escapes  as  soon  as  the 

*  Bunsen  :  Gasometrische  Methoden,  p.  224. 


SOLUTION   OF   GASES.  1 3 

excess  of  pressure  is  removed.  Afterward  the  gas  escapes  more 
slowly,  until  eventually  the  water  contains  no  more  carbonic 
acid  gas  than  it  would  take  up  under  the  conditions  to  which  it 
is  now  exposed.  That  we  really  are  dealing  with  a  supersaturated 
solution  after  the  first  rapid  escape  of  gas,  may  be  shown  by 
dropping  into  the  soda-water  a  teaspoonful  of  sugar,  or  some 
sand,  or  almost  any  powder ;  this  causes  immediate  effervescence 
and  escape  of  gas  by  furnishing  free  surfaces  and  sharp  angles  for 
the  collection  and  liberation  of  the  gas  within  the  liquid. 

Facilitating  gaseous  solution. — In  preparing  a  saturated  solu- 
tion of  a  gas,  the  latter  is  generally  allowed  to  simply  bubble 
through  the  liquid  to  be  saturated  until  the  end  is  attained,  the 
liquid  being  agitated  or  not,  according  to  convenience.  In  the 
case  of  most  gases,  solution  is  facilitated  by  lowering  the  tem- 
perature, as,  for  instance,  by  surrounding  the  vessel  in  which  the 
absorption  takes  place  with  cold  water  or  ice.  This  is  of  especial 
use  when  the  gas  enters  into  chemical  combination  with  the 
liquid,  as  is  true  of  ammonia,  hydrochloric  acid,  etc.,  when  dis- 
solved in  water,  because  the  heat  of  chemical  action  raises  the 
temperature  of  the  solution. 

It  is  sometimes  desirable  to  charge  water  with  gas  under 
increased  pressure  ;  thus  water  is  charged  under  pressure  with 
carbonic  acid  gas,  to  bear  thenceforth  the  name  of  "  soda-water ;  " 
sulphuretted  hydrogen  water,  for  use  in  chemical  laboratories,  is 
also  prepared  similarly. 

Solubility  of  Liquids  in    Water. 

Like  solid  substances,  liquids  differ  among  themselves  as  to 
their  solubility  in  water,  some  liquids,  as  glycerine  and  common 
alcohol,  mix  with  water  in  any  and  all  proportions ;  others,  like 
ether  and  amylic  alcohol,  dissolve  to  a  limited  and  definite  extent ; 
others,  like  some  oils  and  mercury,  seem  to  be  altogether  in- 
soluble, although  by  long  contact  with  the  water  such  insoluble 
liquids  may  undergo  chemical  change,  and  give  up  something  to 
the  water.  It  is  more  difficult  than  with  solids  to  determine 
whether  and  to  what  extent  an  insoluble  or  difficultly  soluble 
liquid  dissolves  in  water,  and  to  distinguish  between  solution  and 
suspension,  especially  if  the  liquid  is  colorless  and  has  nearly  the 
same  refractive  index  as  water.  In  this  case  it  is  impossible  to 


14  INTRODUCTORY  CHAPTER. 

obtain  satisfactory  indications  with  the  eye,  and  complete  separa- 
tion of  suspended  particles  is  often  impossible.  The  solution  of 
a  difficultly  soluble  colorless  liquid  may  sometimes  be  watched 
by  coloring  the  liquid  with  some  substance  which  does  not  inter- 
fere with  the  action.  Thus,  if  amylic  alcohol  be  colored  with  a 
little  iodine,  the  process  of  solution  may  be  followed  more  readily 
than  would  otherwise  be  possible. 

As  in  the  case  of  solids  and  gases,  we  have  the  same  grada- 
tion from  cases  of  marked  chemical  action,  accompanied  by  dis- 
play of  heat  and  decrease  of  bulk,  to  cases  where  we  seem  to  be 
dealing  with  a  simple  mechanical  mixture. 

Distinction  between  Solution  and  Suspension. 

There  is  a  great  deal  of  confusion,  even  among  well-educated 
people,  as  to  the  proper  use  of  the  terms  in  solution  and  in  suspen- 
sion, and  in  the  same  connection  it  may  be  said  that  a  great  deal 
of  confusion  exists  with  reference  to  the  distinction  between 
clear  and  colorless,  terms  which  are  by  no  means  synonymous. 
The  accurate  use  of  the  terms  can  probably  best  be  made  plain 
by  illustrations.  If,  to  take  an  example  already  made  use  of,  we 
put  some  common  salt  into  a  quantity  of  water,  after  a  time  the 
salt  disappears,  the  ultimate  particles  being  distributed  through 
the  water  so  that  they  are  no  longer  distinguishable  by  the  eye, 
even  aided  by  the  most  powerful  microscope ;  the  salt  cannot  be 
removed  by  simple  filtration  ;  and,  although  the  solution  is  some- 
what less  mobile  than  water,  it  is  still  transparent.  This,  as  we 
have  seen,  is  a  case  of  solution.  Suppose  that,  instead  of  the 
salt,  we  take  a  quantity  of  sulphate  of  copper  (blue  vitriol).  The 
phenomena  will  be  similar,  but  the  blue  color  of  the  compound 
shows  itself  in  the  solution.  The  more  concentrated  the  solu- 
tion, the  more  will  its  transparency  be  diminished  on  account 
of  the  depth  of  color ;  it  is  easy,  however,  by  taking  a  thin  layer 
of  the  solution  to  satisfy  one's  self  of  the  transparency  of  the 
liquid  and  of  the  absence  of  suspended  particles.  Such  a  liquid, 
although  colored,  is  clear. 

Suppose,  now,  we  take  some  clay,  shake  it  with  water,  and 
then  allow  it  to  settle.  The  grosser  particles  will  subside  to  the 
bottom  of  the  vessel,  but  the  finer  particles  will  remain  in  sus- 
pension. Very  finely  divided  clay  will  refuse  to  settle  for  weeks, 


DISTINCTION   BETWEEN   SOLUTION  AND   SUSPENSION.         15 

and  sometimes  even  for  months.  In  such  cases  the  liquid  appears 
somewhat  turbid  and  opaque ;  and,  although  the  individual  par- 
ticles are  too  fine  to  be  readily  removed  by  ordinary  filters  and 
too  small  to  be  distinguished  as  particles  by  the  eye,  still  the 
clay  has  not  dissolved,  and  the  very  turbidity  or  opacity  of  the 
liquid  shows  the  presence  of  solid  particles,  although  they  are 
extremely  minute.  Such  an  appearance  is  not  to  be  described  as 
"being  colored,"  although  finely  divided  clay  and  other  material 
may  be  suspended  in  a  liquid  which  does  of  itself  possess  a  dis- 
tinct color.  One  often  meets  with  the  expression,  and  that,  too, 
in  standard  works,  "  the  water  is  discolored  by  clay,"  when  really 
it  is  a  question  of  a  colorless  water  carrying  particles  of  clay  in 
suspension.  As  we  shall  see  further  on,  surface  waters  are  often 
highly  colored  by  vegetable  extractive  matter  in  solution,  but 
the  water  may  at  the  same  time  be  perfectly  clear  and  transpa- 
rent. On  the  other  hand,  pond  waters  often  appear  decidedly 
green ;  but  simple  filtration  gives  a  colorless  water,  and  shows  the 
green  color  to  have  been  due  to  particles  of  green  (vegetable) 
matter  which  were  suspended  in  the  liquid. 

While  for  practical  purposes  there  is  no  difficulty  in  distin- 
guishing that  which  is  really  dissolved  from  that  which  is  merely 
held  suspended,  and  in  applying  the  terms  as  already  indicated, 
it  is  true  that  there  are  substances,  generally  considered  insoluble, 
which  admit  of  such  minute  subdivision  that  the  finer  particles 
will  remain  suspended  in  water  for  months,  giving  in  some  cases 
a  faint  opalescence  to  the  liquid,  but  in  other  cases  apparently 
only  a  color.  Thus,  by  trituration  with  milk-sugar,  metallic  gold 
may  be  reduced  to  so  fine  a  condition  that  it  will  diffuse  through 
water,  giving  it  a  purple  color,  and  it  is  hard  to  say  that  the  gold 
does  not  exist  in  solution;  after  long  standing,  however,  the 
metal  separates  out  and  settles  to  the  bottom  of  the  liquid,  and 
this  separation  may  be  hastened  by  the  addition  of  certain  saline 
solutions.*  The  action  of  the  saline  solution  is  not  fully  under- 
stood, but  it  was  noticed  long  ago  that  these  minute  particles 
showed  under  the  microscope  the  so-called  Brownian  motion,  and 
that  the  addition  of  small  quantities  of  alum,  glue,  lime,  car- 
bonate of  ammonia  or  other  salts,  caused  this  molecular  motion 

*  Buchmann  :  Beobachtungen  und  Untersuchungen  zum  Nachweis  der  Loslich- 
keit  von  Metallen,  etc.     Leipzig,  iSSi,  p.  54. 


I 6  INTRODUCTORY   CHAPTER. 

to  cease,  and  the  particles  to  flock  together  and  settle  out  as 
minute,  amorphous,  curdy  masses.*  The  same  thing  is  illus- 
trated on  the  large  scale  by  the  phenomena  which  take  place 
when  a  river,  like  the  Mississippi,  loaded  with  silt,  meets  the 
waters  of  the  ocean.  Dr.  Hunt  f  found  that  water  taken  near 
the  mouth  of  the  Mississippi  contained  about  ^VTT  °f  suspended 
matter,  mainly  clay,  which  required  from  ten  to  fourteen  days  to 
subside.  He,  however,  observed  that  the  addition  of  sea-water 
or  of  salt,  sulphate  of  magnesia,  alum,  or  sulphuric  acid,  rendered 
the  water  clear  in  from  twelve  to  eighteen  hours,  owing  to  this 
same  flocculation  of  the  suspended  matter. 

*  Naumann  :  Thermochemie,  p.  33. 

|  Proc.  Boston  Soc.  Nat.  Hist.,  xvi,  p.  301. 


WATER  SUPPLY. 

CHAPTER    I. 

DRINKING  WATER  AND   DISEASE. 

WITH  reference  to  their  use  for  town  and  household  supply, 
we  shall  roughly  divide  all  natural  waters  into  four  classes,  as 
follows : 

1.  Rain  water ; 

2.  Surface  water,  including  streams  and  lakes  ; 

3.  Ground  water,  including  shallow  wells  ; 

4.  Deep-seated  water,  including  deep  wells,  artesian  wells,  and 
springs. 

Under  each  of  these  heads  we  shall  study  the  advantages  and 
disadvantages  of  the  particular  class  of  water,  the  liability  of  pol- 
lution, etc. ;  but  first  we  will  consider,  in  a  general  way,  the  con- 
nection which  exists,  or  is  supposed  by  some  to  exist,  between 
drinking  water  and  disease. 

A  water  containing  a  considerable  amount  of  dissolved  sub- 
stances— one  which  could  properly  be  denominated  a  mineral 
water — would  not  be  thought  of  for  a  public  water  supply,  and 
would  seldom  be  used  as  a  regular  beverage  except  for  the  sake 
of  real  or  fancied  medicinal  effect  ;  a  small  amount,  however,  of 
mineral  matter  is  generally  considered  an  advantage.  The  pres- 
ence of  the  substances  which  ordinarily  exist  in  solution  in  natu- 
ral waters  must  not  be  regarded  as  necessary,  because  experience 
on  ship-board  has  shown  that  distilled  water,  properly  aerated,  is 
perfectly  wholesome.  It  appears  that  distilled  water,  soft  sur- 
face water,  and  moderately  hard'*  spring  or  well  water  are  all 
wholesome,  and  may  be  drunk  without  inconvenience  by  persons 
accustomed  to  their  use.  It  is,  however,  true  that  a  person  who 

*  A  hard  water  is,  generally  speaking,  one  which  contains  compounds  of  lime  or 
magnesia  in  solution.     See  pages  33  and  181. 


1 8  WATER   SUPPLY. 

is  in  the  habit  of  drinking  a  soft  water  generally  experiences 
some  derangement  of  the  digestive  organs  on  beginning  to  use 
hard  water,  and  vice  versa.  It  is  contended  by  some  that  the 
human  system  needs  salts  of  lime,  etc.,  that  these  compounds  are 
furnished  in  an  assimilable  form  in  water,  and  that,  consequently, 
a  somewhat  hard  water  is  more  advantageous  for  town  supply  ; 
statistics  have  been  brought  together  to  support  this  view  by 
comparing  the  death  rate  of  various  towns  with  the  hardness  of 
the  water  supply,  but  the  death  rate  depends  upon  too  many 
factors  to  be  used  as  the  chief  argument  in  this  connection.  It 
is,  however,  the  result  of  general  observation  that  a  hard  water 
of  which  the  hardness  is  due  to  salts  of  magnesia  or  to  sulphate 
of  lime  is  not  well  suited  for  drinking,  and  is  injurious  to  most 
persons. 

Waters,  especially  surface  waters,  containing  much  vegetable 
matter  are  also,  in  some  cases,  unwholesome.  The  water  of 
marshes  is  sometimes  the  cause  of  diarrhoea  and  other  diseases 
•of  this  character,  and  is  supposed  by  some  to  cause  malarial  and 
other  fevers  (see  also  page  100).  The  mere  presence  of  vegetable 
organic  matter,  however,  is  not  sufficient  to  produce  these  effects, 
because  many  waters  which  are  quite  deeply  colored  by  vegetable 
matter  are  proved  by  experience  to  be  perfectly  wholesome.* 

While  some  waters  are  thus,  in  their  natural  condition, 
unwholesome  and  may  be  the  cause  of  sickness,  the  attention  of 
sanitarians  and  water  experts  is  directed  nowadays  principally 
to  the  effect  of  water  which  is  polluted  by  the  waste  materials 
from  manufactories  and  dwellings,  or  by  the  sewage  of  towns 
and  cities;  and  it  is  generally  held,  especially  in  England  and  the 
United  States,  that  water  thus  polluted  may  be,  and  frequently 
is,  the  cause  of  certain  specific  diseases.  Before  discussing  this 
question  directly,  it  is  important  to  have  a  general  idea  of  the 
present  prevailing  view  with  reference  to  the  so-called  zymotic 
diseases,  and  to  understand  what  is  meant  by  the  "  germ  theory." 

Many  clear  liquids  containing  organic  matter  of  animal  or 
vegetable  origin — such,  for  instance,  as  infusions  of  hay,  infusion 
of  turnip,  urine,  etc.,  etc.,— if  exposed  to  the  air  gradually  be- 
come turbid  or  cloudy,  or,  perhaps,  a  film  forms  on  the  surface 
of  the  liquid,  or  a  deposit  upon  the  walls  of  the  vessel  which  con. 

*  See,  however,  a  remark  by  Professor  Mallet,  page  26. 


DRINKING  WATER  AND   DISEASE.  19 

tains  it.  The  cause  of  the  turbidity  is  shown  by  the  microscope 
to  be  the  presence  of  countless  minute  organized  bodies — some 
rod-like,  others  globular — which  prove  to  be  capable  of  self-prop- 
agation, and  which  are  endowed  with  motion,  at  least  under  cer- 
tain conditions.  Similar  organisms  are  found  in  the  "  dust  " 
which  floats  in  the  air,  and  which  may  be  collected  by  causing  a 
current  of  air  to  impinge  upon  a  surface  moistened  with  glycer- 
ine ;  they  occur  in  rain  water,  particularly  in  that  which  falls  in 
the  beginning  of  a  shower,  in  surface  waters  and  elsewhere.  They 
are  found  especially  where  there  is  decomposing  organic  matter, 
and  perform  an  active  part  in  promoting  or  producing  the  chem- 
ical changes  which  take  place.  In  certain  diseases  of  men  and  of 
the  lower  animals,  organisms  which,  in  their  general  character, 
are  similar  to  those  thus  described  have  been  found  in  the  blood 
or  in  the  substance  of  various  organs,  and  their  connection  with 
the  disease  seems  to  be  something  more  than  a  coincidence  ; 
there  seems,  indeed,  to  be  a  causal  connection. 

The  micro-organisms  with  which  we  are  now  concerned  are 
referred  to  the  vegetable  kingdom  ;  they  are  regarded  as  related 
both  to  the  fungi  and  to  the  algcz,  and  are  designated  scientifi- 
cally as  schizomycetes  (Spaltpilze,  Nageli)  ;*  their  study  requires 
the  highest  powers  of  the  microscope  and  the  greatest  skill  in 
observation.  The  development  of  certain  forms  has  been  care- 
fully studied,  and  it  is  known  that  they  multiply  not  only  by 
fission — as  Nageli's  classification  impl'es — but  also  by  the  forma- 
tion of  spores  or  permanent  "  germs."  The  "  germ  theory  "  of 
disease  is  that  many  diseases  are  due  to  the  presence  and  propa- 
gation in  the  system  of  these  minute  organisms,  which  are  popu- 
larly spoken  of  under  the  general  name  bacteria,  under  which 
term  are  included  also  organisms  which,  as  far  as  known,  are 
harmless.  Some  of  the  diseases  which  have,  with  more  or  less 
show  of  reason,  been  supposed  to  have  their  cause  in  such  organ- 
isms are  malarial  (intermittent)  fever,  relapsing  fever,  typhus  and 
typhoid,  cholera,  yellow  fever,  diphtheria,  and  tuberculosis. 

*  Nageli  :  Die  niederen  Pilze  in  ihren  Beziehungen  zu  den  Infectionskrankheiten, 
Munich,  1877.  Nageli  distinguishes  three  natural  groups  among  the  lower  fungi  : 
(i)  the  mucorini,  Schimmelpilze,  mould  fungi  ;  (2)  the  saccharomycetes,  Sprosspilze, 
budding  fungi ;  (3)  the  sckizomycetes,  Spaltpilze,  fission  fungi.  The  second  class 
includes  the  organisms  which  produce  the  fermentation  of  wine  and  beer  ;  the  third 
class  includes  the  fungi  of  putrefaction,  the  so-called  bacteria.  The  terms  microbes, 
microzymes,  as  well  as  several  others,  are  also  used  to  include  all  these  micro-organisms. 


2O 


WATER   SUPPLY. 


With  reference  to  specific  distinctions  among  the  organisms 
themselves  observers  are  not  agreed.  Some  would  very  much 
restrict  the  number  of  true  species,  and  refer  the  differences  in 
appearance  and  action  to  differences  in  the  attendant  conditions  ; 
others  believe  that  there  are  many  species,  as  distinct  as  those 
observed  in  higher  organisms,  and  that  each  disease  has  its  own 

9      bacterium ;    they     believe 

*o    co®  *  |     that    the    observed    differ- 

•         S  ® 
1 1Q\     |     ences  are  essential,  and  the 

•    «•   °eae     inability   to   recognize,    in 
all  cases,  satisfactory  spe- 

V  cific  characters  is  due  to  the 

FIG.  3.  a.  Micrococcus  prodigiosus  ;  b.  the  same    imperfection  of  the  means 
in  the  zooglrea  stage  :  c.  M.  Urecc.     650:1.  r      v  ,•  T* 

of  observation.  For  pur- 
poses of  study,  at  any  rate,  the  various  observed  forms  may  be 
classified  in  genera  and  species.  Referring  to  a  few  terms  of 


FIG  4.  a.  Bacterium  termo  ;  b.  Same  in  the  zoogloea  stage  ;  c.  JBacterium  lineola  ; 
d.    Vibrio  rugula  ;  e.    V.  serf  ens  ;  f.   Spirillum  volutans  ;  g.   Sp,  tenue.     650  :  I. 

somewhat  common  occurrence,  the  micrococci  are  globular  or 
oval,  the  bacilli  are  rod-like,  the  vibriones  (vibrios)  are  sinuous, 
and  the  spirilla  are  spiral.  No  attempt  to  represent  these  mi- 
nute organisms  by  cuts  can  be  very  successful.  Figures  3  and  4 
may  serve  to  give  a  rough  idea  of  the  general  appearance  of 
some  of  them. 

The  connection  of  the  bacteria  with  disease  has  been  most 
satisfactorily  made  out  in  the  case  of  splenic  fever  (anthrax, 
charbon  (Fr.),  Milzbrand  (Germ.),  malignant  pustule).  In  this 
disease  the  blood  and  various  organs,  especially  the  spleen,  con- 
tain an  organism  known  as  Bacillus  anthracis.  Koch*  cultivated 

*  Cohn's  Beitrage  zur  Biologic  der  Pflanzen,  ii.  p.  277. 


DRINKING  WATER  AND  DISEASE.  21 

the  organisms  in  appropriate  fluids  outside  of  the  animal  body,  and 
observed  the  development  and  the  formation  of  spores,  and  from 
these  spores  he  reproduced  the  specific  disease  in  living  animals. 
He  found  that  the  organisms  themselves,  as  observed  in  the 
blood,  usually  died  in  a  few  days,  but  that  the  spores  retained 
their  vitality  for  at  least  four  years.  The  Bacillus  anthracis  in 
appearance  is  scarcely  to  be  distinguished  from  the  Bacillus  sub- 
tilts^  a  harmless  form  which  occurs  in  infusions  of  hay,  and  Dr. 
Buchner*  has  been  able,  as  he  claims,  by  a  series  of  cultivations 
to  transform  one  form  into  the  other,  and  from  the  harmless 
Bacillus  subtilis  to  obtain  the  Bacillus  anthracis,  and  to  prove  its 
identity  by  producing  the  well-marked  disease  in  animals.  Nat- 
urally enough  Buchner's  conclusions  are  disputed,  and,  until  his 
results  are  generally  accepted  by  competent  specialists,  they 
cannot  be  looked  upon  by  the  world  in  general  as  showing  more 
than  a  possibility. 

Admitting  the  necessary  presence  of  these  minute  organisms  in 
the  bodies  of  persons  sick  with  certain  diseases,  organisms  which, 
at  least  in  certain  stages  of  their  development,  can  exist  outside 
the  human  body  and  retain  their  vitality  for  a  long  time,  the 
question  arises  how  they  can  find  their  way  into  the  systems  of 
healthy  persons  to  produce  disease.  The  two  most  obvious  of 
the  possible  carriers  of  disease  are  the  air  we  breathe  and  the 
water  we  drink.  We  have  no  difficulty  in  supposing  that  ema- 
nations from  sick  persons,  particulate  or  otherwise,  may  find 
their  way  into  the  air ;  moreover,  the  dejections  of  the  sick  and 
the  water  in  which  their  clothes  or  their  persons  have  been 
washed  may  often  reach  wells  or  other  sources  of  drinking  water. 
Of  these  two  media  the  former,  i.  e.  the  air,  is  a  priori  the  most 
probable,  partly  because  we  take  very  much  more  air  into  our 
lungs  than  we  take  water  into  our  stomachs,  and  also  because 
the  lungs  afford  a  better  chance  for  the  organisms  to  enter  the 
blood  ;  indeed,  some  maintain  that  any  organisms  entering  the 
stomach  are  rendered  harmless  by  the  fluids  therein,  and  that 
the  drinking  water  is,  not  to  be  considered  at  all  as  a  means  of 
conveying  the  germs  of  disease. 

Of  the  diseases  which  are  supposed  to  be  caused  by  these 
micro-organisms — to  be  propagated  by  germs — those  which  have 

*  Sitzb.  d.  math.-phys.  Classe  d.  konigl.  bayer.  Akad.,  1880,  p.  368. 


22  WATER  SUPPLY. 

been,  with  the  greatest  unanimity,  ascribed  to  the  use  of  impure 
drinking  water  are  typhoid  fever  and  cholera.  With  reference 
even  to  these  diseases,  however,  there  has  been  much  discussion 
and  controversy  between  the  adherents  and  the  opponents  of  the 
"drinking-water  theory"  since  1848,  when  Snow,  Budd,  and 
others  in  England  ascribed  the  spread  of  the  cholera  then  prev- 
alent to  the  drinking  of  water  fouled  by  the  dejections  of  cholera 
patients.  It  would  be  unprofitable,  in  brief  space,  to  attempt  to 
review  the  numerous  cases  on  record  where  the  coincidences 
between  impure  water  and  cholera  (and  other  diseases)  have 
been  so  marked  as  to  lead  able  and  careful  investigators  to  believe 
in  the  existence  of  cause  and  effect.  The  most  able  opponent 
of  the  theory  is  Professor  Pettenkofer,  of  Munich,  who  holds 
that  in  these  cases  there  is  coincidence  only,  and  that  other  cir- 
cumstances, and  notably  the  character  of  the  ground  and  the 
condition  of  ground  water,  have  been  overlooked  in  the  investi- 
gations. He  and  his  sympathizers  also  bring  forward  many 
instances  where  the  connection  between  a  particular  outbreak  of 
a  specific  disease  and  the  drinking  water  previously  used  by  those 
attacked  is  not  only  not  obvious,  but  absolutely  out  of  the 
question. 

Even  the  most  earnest  advocates  of  the  drinking-water  theory 
must  admit  that  the  theory  is  by  no  means  proved,  in  the  sense 
in  which  a  mathematical  proposition  may  be  proved,  and  it  cer- 
tainly cannot  be  asserted  that  the  drinking  water  is  the  only 
means  by  which  the  zymotic  diseases  may  be  propagated  ;  the 
coincidences,  however,  if  coincidences  they  be,  are  most  remark- 
able, and  every  year  adds  to  their  number.  To  choose  a  single 
example  from  the  multitude  which  are  accessible,  we  may  take 
the  case  of  an  outbreak  of  typhoid  fever  in  North  Boston,  Erie 
Co.,  N.  Y.,  which  occurred  in  the  year  1843,  consequently  before 
the  connection  between  typhoid  and  drinking  water  had  become 
a  theory.  The  community  consisted  of  nine  families  (forty-three 
persons),  and  typhoid  fever  had  never  been  known  in  the  vicinity 
until  in  the  year  named  a  sick  traveler  took  lodging  at  the  tavern, 
and  twenty-eight  days  thereafter  died  of  what  was  pronounced 
by  the  physicians  to  be  typhoid  fever.  The  disease  spread,  twen- 
ty-eight persons  in  all  were  attacked,  and  only  three  families  es- 
caped. These  three  families  were  the  only  ones  which  did  not  use 
the  well  of  the  tavern,  two  of  them  on  account  of  distance,  and  one 


DRINKING  WATER  AND   DISEASE.  23 

on  account  of  a  feud  between  them  and  the  inn-keeper.  The 
latter  family  lived  within  four  rods  of  the  tavern.  The  physi- 
cians, at  that  time,  ascribed  the  communication  of  the  disease  to 
a  "  contagium  contained  in  the  emanations  from  the  body,"  but 
the  people  charged  the  family  referred  to  with  poisoning  the  well, 
so  marked  was  the  coincidence.  Subsequently,  Dr.  Flint,  in 
reviewing  the  case,  regards  it  as  "  vastly  probable,  if  not  certain," 
that  the  disease  was  communicated  by  the  drinking  water,  the 
source  of  which  was  so  situated  that  it  must,  in  all  probability, 
have  been  contaminated  by  the  dejections  of  the  first  patient.'* 

Many  other  instances  might  be  cited  where  a  number  of  fam- 
ilies or  persons  using  the  same  well  or  other  source  of  water 
supply  have  become  victims  to  the  disease,  which  does  not,  at 
the  time,  appear  elsewhere ;  there  are  many  instances  where  the 
closing  of  the  suspected  source  of  supply  has  at  once  put  a  stop 
to  the  further  spread  of  the  disease;  there  are  also  instances 
where  people  have  assembled  in  numbers  on  account  of  some 
celebration,  and  sickness  has  followed  in  the  case  of  a  large  pro- 
portion of  those  who  have  used  a  certain  water,  while  the  others 
have  not  been  affected ;  latterly  there  have  been  cases  where 
sickness  has  broken  out  among  families  obtaining  their  milk  from 
the  same  source,  and  investigation  has  shown  that  impure  water 
was  used  in  the  dairy.  The  most  weighty  criticism  urged  against 
the  acceptance  of  the  theory  which,  in  such  cases  as  those  men- 
tioned, regards  the  water  as  the  cause  of  disease,  is  that,  in  the 
investigations  made,  sufficient  attention  has  not  been  paid  to 
other  features  of  the  circumstances  and  surroundings  which 
might,  with  equal  likelihood,  be  factors  in  the  production  of  dis- 
ease. No  doubt,  in  some  instances  this  criticism  is  just ;  but  if 
we  rule  out  all  cases  where  the  observations  are  manifestly  im- 
perfect there  still  remain  instances  enough  to  make  the  connec- 
tion between  the  water  drank  and  the  disease  contracted  ex- 
tremely probable.  As  this  is  a  matter  which,  in  the  present  state 
of  science,  cannot  be  absolutely  proved  or  disproved,  the  duty 
of  those  who  have  to  advise  or  to  decide  in  matters  relating  to 
water  supply  is  perfectly  clear;  it  is  to  err  on  the  side  of  safety, 
to  admit  the  hypothesis  that  specific  diseases  may  be  conveyed 

*  Austin  Flint,  M.D.     Reports  and  Papers  Am.  Public  Health  Assoc.,  i,  pp.  164- 
172. 


24  WATER  SUPPLY. 

by  the  drinking  water,  and  to  guard  all  sources  of  domestic  and 
public  supply  from  the  possibility  of  contamination  by  the  dejec- 
tions of  persons  sick  with  zymotic  diseases  and  by  excremental 
matter  generally. 

What  has  hitherto  been  said  has  had  reference  to  the  pollu- 
tion of  water  by  excremental  matter  from  persons  actually  sick 
with  communicable  diseases.  Any  pollution,  however,  by  ex- 
cremental matter  should  be  guarded  against,  partly  because  at 
some  time  the  discharges  of  sick  persons  may  accompany  the 
other  excremental  matter,  and  partly  because  there  is  evidence 
that  under  certain  circumstances  the  discharges  of  healthy  per- 
sons and  animal  matter  generally  may  give  rise  to  disease.  Under 
what  circumstances  excremental  matter  becomes  dangerous  we 
do  not  know.  It  is  certain  that  it  is  often  taken  into  the  stom- 
achs of  men  and  animals,  apparently  without  doing  any  harm. 
Fish  often  gather  about  the  mouths  of  sewers  and  seem  to  thrive ; 
the  Norwegians  save  up  in  summer  the  dung  of  the  horses  and 
sheep  to  serve  as  food  for  the  cattle  in  winter ;  and  in  many 
localities  where  wood  is  scarce,  dried  animal  excrement  is  used 
for  fuel  and  in  direct  contact  with  the  food  to  be  cooked.  Dr. 
Emmerich,  who  does  not  believe  in  the  "  drinking-water  theory," 
himself  drank  dilute  sewage  for  a  number  of  days  in  succession, 
and  persuaded  several  of  his  patients  to  do  likewise,  with  no  ill 
effect :  *  moreover,  the  experience  of  every  water-analyst  shows 
that  there  are  many  grossly  polluted  wells  which  have  never  been 
known  to  produce  disease.  It  is  thus  difficult  to  believe  that  in 
ordinary  excremental  matter  there  is  any  specific  poison ;  but  as 
there  seems  to  be  abundance  of  circumstantial  evidence  to  show 
that  disease  does,  at  times,  follow  the  use  of  water  which  has 
received  excremental  pollution,  we  are  forced  to  believe  either 
that  the  organic  matter  undergoes  change,  and  in  certain  stages 
of  decomposition  can  produce  sickness,  or  that  it  is  accompanied 
by  something,  not  yet  isolated,  which  is  the  real  morbific  princi- 
ple, or,  indeed,  that  its  effect  is  to  predispose  to  disease,  which 
fails  to  attack  others  not  thus  predisposed. 

Next  in  importance  to  excremental  matters  is  the  refuse  from 
slaughter-houses,  wool-pulling  establishments,  tanneries,  etc., — 
animal  refuse,  in  fact,  from  various  sources.  Here  we  are  met. 

*  Zeitschrift  fur  Biologic,  xiv   (1878),  p.  591. 


DRINKING  WATER  AND   DISEASE.  2$ 

by  the  objection  that  much  animal  matter  is  consumed  in  a  more 
or  less  decayed  condition  with  apparent  harmlessness,  as  for 
instance,  ripe  game  or  ripe  cheese :  but,  to  offset  this,  there  are 
numerous  cases  on  record  where  sickness  has  arisen  from  spoiled 
meat,  especially  in  the  form  of  sausages  and  potted  meats.  But, 
after  all,  as  stated  above,  the  evidence  which  connects  disease 
with  polluted  water  is  purely  circumstantial,  and  the  amount  of 
organic  matter,  even  in  waters  classed  as  dangerous,  is  so  small, 
that,  as  pointed  out  by  Professor  Mallet,*  it  furnishes  "important 
evidence  against  any  chemical  theory  of  the  production  of  dis- 
ease from  this  source,  any  theory  based  on  the  simple  assumption 
that  some  of  the  chemical  products  of  the  decomposition  of 
organic  matter  are  poisonous  or  noxious  in  their  effect  upon  the 
human  system."  Instancing  two  particular  waters,  he  says  :  "  If 
the  whole  of  the  organic  carbon  and  nitrogen  found  in  such  waters 
as  Nos.  35  and  36,  of  the  highly  dangerous  character  of  which 
there  can  scarcely  be  a  doubt,  existed  as  strychnine,  it  would  be 
necessary  to  drink  about  a  half  a  gallon  of  the  water  at  once  in 
order  to  swallow  an  average  medicinal  dose  of  the  alkaloid.  It 
is  not  easy  to  believe  that  the  ptomaines,  or  any  other  chemical 
products  of  the  putrefactive  change  as  yet  observed,  can  possess 
an  intensity  of  toxic  power  so  very  much  greater  than  that  of 
the  most  energetic  of  recognized  poisons.  While  numerous  facts 
go  to  support  the  belief  that,  not  to  the  effect  of  any  chemical 
substances  (such  effect  necessarily  standing  in  definite  relation  to 
their  quantity),  but  to  the  presence  of  living  organisms,  with  their 
power  of  practically  unlimited  self-multiplication,  we  must  in  all 
probability  look  for  an  explanation  of  most,  at  any  rate,  of  the 
mischief  attributable  to  drinking  water,  it  is  of  course  possible 
that  indirectly  a  large  amount  of  organic  matter  in  water  may  be 
more  dangerous  than  a  smaller  quantity,  as  furnishing  on  a  greater 
scale  the  suitable  material  and  conditions  for  the  development  of 
noxious  as  well  as  harmless  organisms." 

Although  there  are  many  substances  of  vegetable  origin  which 
are  violent  poisons,  such  as  the  vegetable  alkaloids,  for  example, 
it  is  generally  held  that  refuse  of  vegetable  origin  is  of  much  less 
importance  as  a  source  of  pollution  than  that  coming  from  animal 
sources.  This  is  probably  true,  in  general,  but  it  is  well  known 

*  National  Board  of  Health  Bulletin,  May  27,  1882. 


26  WATER  SUPPLY. 

that  the  vegetable  refuse  from  certain  manufacturing  operations 
may  be  very  offensive :  such,  for  instance,  is  the  refuse  from 
starch  factories,  the  water  in  which  flax  has  been  retted,  etc. 
That  such  water  would  be  unfit  to  drink,  unless  enormously 
diluted,  one  can  hardly  doubt.  To  quote  again  from  Professor 
Mallet : 

"If  the  theory  be  accepted,  which  has  so  much  in  its  favor, 
attributing  the  production  of  disease  by  organic  matter  in  drink- 
ing water  not  to  any  specifically  poisonous  substance  or  substances, 
but  to  the  presence  and  action  of  living  organisms,  it  seems  quite 
conceivable  that  a  water  containing  organic  matter  of  any  kind, 
including  vegetable  matter,  may  be  harmless  at  one  time,  and 
harmful  at  another,  when  perhaps  a  different  stage  of  fermenta- 
tion or  putrefactive  change  may  have  been  entered  upon,  and 
special  organisms  may  have  made  their  appearance  or  entered 
upon  a  new  phase  of  existence.  Thus,  there  might  possibly  be 
safety  in  drinking  a  peaty  water,  or  water  filtered  through  beds 
of  dead  forest  leaves,  when  fresh  ;  danger  when,  after  a  certain 
amount  of  atmospheric  exposure,  bacterial  organisms  had  become 
developed ;  and  safety  again,  perhaps,  after  the  growth  of  such 
organisms  had  fallen  off,  and  more  or  less  of  the  available  organic 
matter  had  been  consumed." 

However  views  may  differ  as  to  the  possible  injury  from  this 
or  that  particular  form  of  contamination,  we  are  safe  in  accepting 
the  two  following  principles  as  fundamental  guides  in  the  selec- 
tion of  a  water  for  water  supply  : 

1.  A  water  suitable  for  domestic  supply  must  be  free  from  all 
substances  which  are  known  to  produce  an  injurious  effect  on  the 
human  system,  or  which  are  suspected  with  good  reason,  or  on 
good  authority,  to  produce  such  an  effect. 

2.  The  water   should  be,  as  far  as  practicable,  free  from  all 
substances  and  from  all  associations  which  offend  the  general 
aesthetic  sense  of  the  community,  and  thus  affect  the  system 
through  the  imagination,  even  if  there  is  good  reason  to  suppose 
that  it  is  in  itself  perfectly  harmless. 

The  first  of  these  principles  needs  no  argument  to  justify  it ; 
with  reference  to  the  second,  a  word  or  two  may  be  said.  Dr. 
Emmerich,  even,  admits  that  not  every  one  could  drink  dilute 
sewage  as  he  did,  because  the  mere  idea  of  so  doing,  or  the  sight 
of  a  floating  hair  or  other  unattractive  object,  would  no  doubt 


DRINKING  WATER  AND   DISEASE.  2/ 

with  many  persons  produce  disgust  and  nausea,  and,  if  the  water 
were  forced  down,  it  would  most  likely  be  thrown  up  again. 
While  there  is  no  doubt  of  this  power  of  the  imagination  and  its 
effect  on  the  physical  system,  common  sense  must  fix  a  limit  to 
the  application  of  this  second  principle,  and  some  latitude  must 
be  allowed  according  to  the  circumstances  of  the  particular  case. 
Thus,  if  a  lake  is  chosen  as  the  most  available  source  of  supply, 
the  fact  that  some  persons  bathe  in  its  waters  can  hardly  condemn 
it  for  use ;  and  the  fact  that  a  limited  amount  of  town  drainage 
finds  its  way  into  a  stream  does  not  necessarily  prevent  its  being 
used  at  some  portion  of  its  course,  although  a  stream  once  seri- 
ously polluted  should  not  be  looked  upon  as  an  available  source 
of  supply.  Again,  most  persons  naturally  object  to  v/ater  as 
muddy  as  that  of  many  of  our  Western  streams,  in  spite  of  the 
favorable  testimony  of  those  in  the  habit  of  using  it,  but  by  a 
short  residence  in  St.  Louis,  for  instance,  most  persons  soon  be- 
come accustomed  to  the  turbidity.  The  turbidity  is  a  real  objec- 
tion to  the  water,  but,  in  the  case  of  a  water  like  that  of  the 
Missouri,  a  town  would  not  be  justified  in  postponing  the  intro- 
duction of  the  water  because  it  was  not  able  at  the  same  time  to 
adopt  a  scheme  for  its  thorough  filtration.  In  the  same  way,  if 
the  only  objection  to  a  river  or  pond  water  is  a  yellow  or  brown- 
ish-yellow color  derived  from  vegetable,  especially  peaty  matter, 
the  water  need  not  be  condemned,  although  most  persons  would 
prefer  a  colorless  water. 

Undoubtedly,  the  best  water  for  drinking  is  a  moderately  soft 
spring  water,  in  which  all  possibility  of  contamination  is  out  of 
the  question.  Unfortunately,  however,  it  is  comparatively  sel- 
dom that  such  water  is  available  in  quantities  sufficient  for  the 
supply  of  large  towns.  Many  spring  waters  are  so  hard  that, 
while  not  unsuited  for  drinking,  they  are  unsuited  for  many  man- 
ufacturing uses,  for  use  in  steam  boilers,  for  washing  and  culinary 
purposes.  It  is  a  mistake  to  claim  that  the  water  which  is  abso- 
lutely best  for  drinking  must  be.  chosen,  at  any  expense,  as  a  town 
supply  ;  when  a  soft  surface  water,  free  from  appreciable  pollution 
can  be  obtained,  it  entails  a  very  serious  and  constant  expense  to 
reject  it  in  favor  of  a  hard  water,  which  may,  to  be  sure,  be  clearer 
to  the  eye  and  somewhat  more  pleasant  to  the  taste.  There  are 
surface  waters  and  there  are  surface-water  supplies  which  are  un- 
doubtedly bad,  but  a  good  surface  water,  such  as  may  be  taken 


28  WATER  SUPPLY. 

directly  from  many  streams  or  such  as  may  be  obtained  from  deep 
lakes  and  from  proper  storage  basins,  is  perfectly  well  suited  for 
domestic  use  or  for  town  supply.  There  are  some  who  maintain 
an  opinion  contrary  to  that  which  has  been  expressed.  The 
Vienna  Commission  in  1864,  rejected  surface  waters  from  among 
the  waters  suitable  for  domestic  use,  on  the  ground  of  their  vari- 
able temperature  (see  page  91)  and  their  liability  to  pollution. 
The  German  Public  Health  Association,  at  the  Danzig  meeting 
in  1880,  by  a  small  majority  and  after  a  lively  discussion,  adopted 
a  resolution  to  the  effect  that  spring  water  or  properly  protected 
ground  water  were  the  only  admissible  sources  of  supply ;  but  two 
years  later  this  dictum  was  modified  so  as  to  include  filtered  river 
water  as  fulfilling  the  required  conditions,  and  this  conclusion  is 
sanctioned  by  practice  and  experience. 


CHAPTER  II. 

WATER    ANALYSIS. 

IT  is  not  the  purpose  of  the  present  chapter  to  give  in  detail 
all  the  various  methods  employed  in  the  analysis  of  water,  or  to 
serve  as  a  guide  to  those  wishing  to  make  such  analyses.  Ex- 
cellent manuals  on  this  subject  already  exist.  An  attempt  will 
be  made,  however,  to  explain  what  is  the  meaning  of  the  various 
terms  used  in  the  reports  of  water  analysis,  and  to  indicate  the 
significance  to  be  attached  to  the  figures  given. 

For  this  discussion  we  may  classify  the  substances  occurring 
in  a  natural  water  according  to  the  following  scheme  : 


i.  Suspended  matter  ......         °c'      C  Animal. 

'  '  (  Vegetable. 


Suspended  matter.  —  The  determination  of  the  amount  of  sus- 
pended matter  is  principally  of  value  with  reference  to  possible 
schemes  of  sedimentation  or  filtration.  The  operation  is  com- 
monly conducted  by  passing  a  measured  quantity  of  water  through 
a  paper  filter  which  has  previously  been  dried  at  100°  C.  and  then 
weighed  ;  after  the  passage  of  the  water,  the  filter  with  its  con- 
tents is  again  dried  at  100°  and  weighed  for  the  second  time. 
The  difference  between  the  two  weights  is  the  weight  of  the 
suspended  matter.  The  filter  with  its  contents  is  then  trans- 
ferred to  a  platinum  crucible,  and  the  crucible  is  heated  until  the 
filter  has  been  burned  up  and  the  organic  matter  destroyed. 
The  weight  of  what  remains,  minus  the  weight  of  the  ash  which 
a  filter,  such  as  was  used,  is  known  to  leave,  is  the  weight  of  the 
inorganic  or  mineral  portion  of  the  suspended  matter.  Another 
method,  which  is  exact  enough  for  most  purposes,  consists  in 
evaporating  a  measured  quantity  of  the  water  in  its  natural  con- 
dition, and  an  equal  quantity  which  has  been  filtered  through 
paper.  The  residues  in  the  two  cases  are  weighed  and  the  dif- 
ference is  approximately  the  weight  of  the  matter  which  was  in 
suspension. 


3O  WATER   SUPPLY. 

It  is  quite  as  important  to  know  the  character  of  the  suspended 
matter  as  to  know  its  absolute  amount.  It  is  desirable  to  know 
whether  it  settles  readily,  and,  if  it  contains  much  organic  matter, 
whether  this  is  mainly  of  animal  or  of  vegetable  origin.  Some 
information  as  to  the  latter  point  may  be  obtained  by  observing 
the  appearance  and  odor  when  it  is  strongly  heated,  but  micro- 
scopical examination  is  of  the  greatest  service  in  this  connection. 

In  expressing  in  figures  the  results  of  the  analysis,  a  consid- 
erable difference  exists  in  the  practice  of  different  chemists  as  to 
the  unit  to  be  employed.  The  methods  of  expression  in  most 
common  use  are  the  following : 

(1)  In  grains  to  the  English  (imperial)  gallon,  which  meas- 
ures 277  cubic  inches  and  is  equivalent  to  10  Ibs.,  or  70,000  grains, 
of  pure  water.     This  method  is  still  quite  common  in  England. 

(2)  In  grains  to  the  U.  S.  gallon,  which  measures  231  cubic 
inches  and  is  equivalent  to  58,372  -f  grains  of  pure  water.     This 
method  is  very  common  in  the  United  States. 

(3)  On  a  decimal  basis,  as  so  many  parts  (by  weight)  in  1,000, 
10,000,  100,000,  or  1,000,000  parts  of  the  water  according  to  the 
amount  of  dissolved  matter  present.     Thus,  mineral  waters  are 
usually  reported  as  containing  so  many  parts  in  1,000  or  in  10,000 
parts,  while  for  potable  waters  parts  in  100,000  or  1,000,000  are 
employed.     The  preference  of  the  author  is  decidedly  for  "  parts 
in  100,000,"  which  is  now  generally  used  in  France  and  Germany; 
also  in  the  Reports  of  the  Rivers  Pollution  Commission  of  Great 
-Britain,  and,  in  this  country,  in  the  reports  of  the  National  and 
of  many  State  Boards  of  Health. 

(4)  As  so  many  milligrams  to  the  liter.     This  would  be  equiv- 
alent to  so  many  parts  in  1,000,000  if  the  water  possessed  the 
same  density  as  pure  water  ;  that  is,  if  a  liter  of  the  water  actually 
weighed  1,000  grams.     Practically,  the  error  introduced  by  meas- 
uring instead  of  weighing  the  water  taken  for  analysis,  is,  in  the 
case  of  most  potable  waters,  less  than  the  error  of  analysis,  thus: 


If  the  specific  grav- 
ity is 

So  many  milligrams 
to  the  liter 

Equal  so  many  parts 
in  1,000,000. 

Diff. 

.OIO 

5-000 

4-950 

0.050 

.010 

10.000 

9.901 

0.099 

.020 

5.000 

4.902 

0.098 

.020* 

10.000 

9.804 

o.  196 

.040 

5.000 

4.808 

0.192 

.040 

10.000 

9.615 

0.385 

*  The  specific  gravity  of  sea  water  is  about  1.029. 


WATER  ANALYSIS.  3! 

In  the  case  of  mineral  waters,  sea-water,  etc.,  the  difference 
is  too  great  to  be  neglected ;  and,  in  such  cases,  it  should  always 
be  distinctly  stated  whether  the-  results  are  in  milligrams  to  the 
liter,  or  in  parts  in  1,000,000  by  weight. 

Dissolved  substances. — Gases. — Almost  all  gases  dissolve  in 
water  to  a  greater  or  less  extent.  It  is  seldom,  however,  that  a 
water  which  is  proposed  or  used  as  a  source  of  supply  contains 
appreciable  quantities  of  any  gases  other  than  those  of  the 
atmosphere — oxygen,  nitrogen,  and  carbonic  acid.  These  gases 
are  present  in  very  varying  proportions.  Oxygen  is  found  in 
all  waters  which  have  been  exposed  to  the  air.  The  waters  of 
artesian  wells  often  contain  none  of  this  gas,  but  they  absorb  it 
at  once  on  reaching  the  air ;  waters  from  highly  polluted  sources 
are  also  deficient  in  oxygen.  Nitrogen  occurs  to  a  greater  or 
less  extent  in  all  waters,  and  in  some  mineral  or  effervescent 
waters  it  forms  the  largest  part  of  the  dissolved  gases.  Carbonic 
acid  is  present  in  all  potable  waters;  its  presence  is  of  important 
influence  in  determining  the  amount  of  carbonate  of  lime  which 
a  given  water  can  contain,  and  the  solvent  effect  of  water  on 
many  minerals  is  due  to  the  presence  of  carbonic  acid. 

It  was  formerly  the  general  custom  to  make  a  complete  quan- 
titative analysis  of  the  various  gases  present  in  a  sample  of  water 
under  examination.  The  analysis  was  made  by  boiling  out  the 
gases  from  a  measured  quantity  of  water  and  submitting  the 
mixture  obtained  to  the  accurate  but  tedious  methods  of  gas 
analysis.  When,  however,  as  often  happened,  the  determinations 
were  not  made  on  the  spot,  but,  on  the  contrary,  on  samples  of 
water  which  had  been  standing  for  days  or  for  weeks,  they  were 
nearly  worthless,  and  are  now  rarely  made  except  in  the  case  of 
mineral  waters.  In  fact,  at  the  present  time,  it  is  seldom  that 
the  amount  of  any  dissolved  gas  is  determined,  except  oxygen ; 
and  for  determining  the  amount  of  oxygen  in  a  given  water,  a 
process  was  devised  a  few  years  ago  by  Schiitzenberger  which 
admits  of  being  performed  with  sufficient  accuracy  out  of  doors. 
A  water  which  is  polluted  by  decaying  organic  matter  not  only 
calls  upon  the  air  about  it  to  furnish  oxygen  for  the  combustion 
of  the  decaying  matter,  but  uses  up  in  the  process  more  or  less, 
sometimes  all,  of  the  oxygen  previously  dissolved  in  the  water. 
The  amount  of  dissolved  oxygen  is  thus  considered  by  some  to 
be  an  indication,  in  the  inverse  direction  of  course,  of  the 


32  WATER  SUPPLY. 

amount  of  impurity  present.  An  example  of  the  application  of 
this  method  may  be  found  on  page6i.  The  results  thus  ob- 
tained are  of  value,  as  in  this  case,  in  tracing  the  course  of  the 
same  polluted  stream,  but  a  knowledge  of  the  absolute  amount 
of  dissolved  oxygen  gives  no  means  of  judging  of  the  purity  of  a 
single  sample  of  water ;  for,  not  only  is  the  water  of  some  arte- 
sian wells  free  from  oxygen,  as  stated  above,  but  the  ground 
water  generally  and  the  water  of  unpolluted  springs  and  deep 
wells  is  also  deficient  in  oxygen. 

In  the  case  of  all  the  gases,  the  amount  present  is  indicated 
as  so  many  cubic  inches  to  the  gallon,  or  as  so  many  cubic  centi- 
meters to  the  liter. 

Total  solids  in  solution. — The  determination  of  the  total 
amount  of  dissolved  matter  is  made  by  evaporating  a  measured 
quantity  of  water  to  dryness  in  a  weighed  platinum  dish,  drying 
at  some  definite  temperature,  and  then  weighing  the  dish  with  its 
contents.  The  determination  is,  at  the  best,  a  rough  one,  and 
the  solid  matter  obtained  by  evaporation  does  not  exactly  repre- 
sent what  was  originally  in  solution.  In  the  evaporation  some 
substances  pass  off  with  the  steam  and  are  lost.  Other  substan- 
ces are  changed  in  character  by  the  treatment.  If  the  residue  be 
dried  at  the  temperature  of  boiling  water,  which  is  that  most  com- 
monly employed,  some  of  the  salts  retain  water  of  crystalliza- 
tion ;  at  a  somewhat  higher  temperature,  even  as  low  as  140°  C., 
the  organic  substances  begin  to  be  decomposed  and  lose  weight. 
In  spite  of  this,  some  chemists  use  a  temperature  as  high  as  180°  C. 
It  is  generally  of  no  importance  for  sanitary  purposes  that  the  de- 
termination should  be  exact,  for  it  is  of  no  consequence  whether 
a  water  leaves  4  or  6  parts  of  "  total  solid  residue,"  whether  it 
leaves  10  or  12  parts,  but  in  the  case  of  periodical  examinations 
of  the  same  water  the  determinations  should  be  made  in  the  same 
way  at  all  times,  in  order  that  they  may  be  compared  with  each 
other. 

It  is  seldom  necessary  for  sanitary  purposes  to  make  a  com- 
plete analysis  of  the  water  and  to  determine  the  amount  of  each 
of  the  various  compounds  which  make  up  the  "total  solids."  A 
few  of  the  mineral  constituents  are  almost  always  determined  for 
special  reasons,  and,  in  individual  cases,  others  may  be  estimated, 
but,  as  a  rule,  the  indications  of  qualitative  tests  suffice.  In  a 
water  which  has  passed  through  metal  pipes,  or  which  receives 


WATER  ANALYSIS.  33 

the  flow  from  mines,  or  from  manufacturing  operations,  poison- 
ous metals  should  be  looked  for ;  lead  and  copper  are  the  most 
common,  and  less  than  one-tenth  of  a  grain  of  lead  to  the  gallon 
has  been  known  to  do  harm ;  arsenic  is  frequently  found  in  run- 
ning streams  and  sometimes  in  water  which  contains,  or  rather 
which  deposits,  oxide  of  iron,  but  the  amount  is  usually  too  small 
to  notice;  arsenic  has,  however,  been  the  cause  of  well-pollution 
in  the  neighborhood  of  manufactories  of  aniline  colors. 

Chlorine. — Chlorine  is  almost  always  determined  quantitatively. 
It  will  be  understood  that  this  element  never  occurs  free  in  nat- 
ural waters,  but  always  in  combination  as  chloride  of  sodium  or  as 
some  other  chloride.  The  amount  is  generally  reported  as  so  much 
chlorine,  although  some  analysts  prefer  to  calculate  the  corre- 
sponding amount  of  chloride  of  sodium  (common  salt),  and  report 
in  this  way.  Although  chlorides  are  present  in  all  soils  and  nat- 
ural waters,  the  quantity  in  the  uncontaminated  water  of  most 
regions  is  very  small.  Where  this  is  known  to  be  the  case,  the 
presence  of  any  noticeable  amount  of  chlorine  (say  much  more 
than  I  part  in  100,000)  indicates  contamination  from  human 
sources,  as  chloride  of  sodium  is  a  constant  constituent  of  sewage 
and  of  animal  refuse  in  general,  and  is  not  eliminated  to  any  con- 
siderable extent  either  in  passing  through  the  soil  or  by  the  action 
of  vegetation.  Chlorides  remain  as  evidences  of  past  contami- 
nation after  all  other  evidences  have  ceased  to  exist,  although 
the  amount  present  does  not  bear  any  constant  proportion  to  the 
amount  of  polluting  substances  which  are  or  have  been  in  the 
water. 

Hardness. — A  determination  of  the  "  hardness  "  usually  finds 
a  place  in  the  examination  of  a  water  proposed  as  a  source  of 
supply.  The  determination  is  made  by  taking  advantage  of  one 
of  the  properties  which  make  hard  water  undesirable — namely,  the 
property  of  destroying  soap.  A  solution  of  soap  is  prepared  of 
such  a  strength  that  a  measured  quantity  of  it  is  exactly  destroyed 
or  neutralized  by  a  known  amount  of  some  compound  of  lime. 
The  lime  compound  is  previously  dissolved  in  a  certain  amount, 
say  loo  cubic  centimeters,  of  water,  and  the  test  is  made  by  ascer- 
taining how  much  of  this  same  standard  soap  solution  is  destroyed 
by  loo  c.c.  of  this  particular  water.  The  hardness  of  another 
portion  of  the  water  is  determined  after  boiling  for  some  time ; 
this  is  called  "permanent  hardness"  and  is  due  to  sulphates 
3 


34  WATER  SUPPLY. 

and  other  soluble  compounds  of  lime  and  magnesia.  The  total 
hardness,  less  the  permanent  hardness,  is  the  "  temporary  hardness" 
and  is  due  to  the  bicarbonates  of  lime  and  magnesia,  which  are 
decomposed  by  boiling.  The  hardness  is  generally  expressed  in 
degrees,  which  have  different  significations  in  different  countries. 
In  England,  where  the  process  originated,  a  degree  of  hardness 
corresponds  to  a  grain  of  carbonate  of  lime  in  one  imperial  gallon 
of  water;  for  example,  a  water  of  5  degrees  hardness  means  a 
water,  each  gallon  of  which  contains  compounds  of  lime  or  mag- 
nesia or  both  equivalent  in  soap-destroying  power  to  5  grains  of 
carbonate  of  lime.  In  Germany  the  degrees  of  hardness  indicate 
the  equivalent  of  so  many  parts  of  oxide  of  calcium  (quicklime) 
in  100,000  parts  of  water.  In  France  the  degrees  mean  so  many 
parts  of  carbonate  of  lime  in  100,000  parts  of  water.  In  America, 
in  spite  of  the  anomaly,  many  express  the  hardness  in  English 
degrees,  i.  e.,  in  grains  to  the  imperial  gallon,  while  the  other  re- 
sults are  given  in  grains  to  the  United  States  gallon.  The 
French  system  of  parts  in  100,000  is,  however,  to  be  preferred. 

Combined  nitrogen. — Nitrogen  exists  in  potable  waters  under 
a  variety  of  forms  of  combination.  Animal  matter  generally  con- 
tains nitrogen,  as  do  also  many  substances  of  vegetable  origin : 
this  is  usually  spoken  of  as  "organic  nitrogen."  Nitrogen  also 
exists  in  the  form  of  ammonia  and  ammoniacal  salts,  and  these 
compounds  are  due  almost  entirely  to  the  decomposition  of  nitrog- 
enous vegetable  and  more  especially  animal  matters.  For  this 
reason,  although  in  itself  harmless,  the  ammonia  is  determined 
quantitatively.  The  amount  present,  even  in  a  polluted  water,  is 
small,  and  when  expressed  in  figures — as  in  the  various  tables  on 
following  pages — seems  insignificant,  nevertheless,  as  a  sign  of  or- 
ganic pollution,  its  determination  should  not  be  omitted.  Although 
the  amount  of  ammonia  is  so  small — a  water  containing  o.i  part 
by  weight  in  100,000  parts  of  the  water  being  grossly  polluted— 
the  figures  are  entitled  to  confidence  because  the  method  usually 
employed  is  very  delicate,  and,  by  a  process  of  distillation,  the 
ammonia  in  a  large  volume  of  water  may  be  concentrated  into  a 
small  bulk.  The  "  Nessler  test,"  which  is  employed  in  estimating 
ammonia,  is  capable  of  detecting  I  part  by  weight  of  ammonia  in 
20,000,000  parts  of  water. 

A  great  diversity  of  opinion  exists  as  to  the  value  which  at- 
taches to  a  determination  of  the  exact  amount  of  nitrogen  pres- 


WATER  ANALYSIS.  35 

ent  as  nitrites  and  nitrates.  The  compounds  themselves,  in  small 
amounts,  are  no  doubt  harmless,  but  it  is  also  true  that  they  re- 
sult from  the  oxidation  of  nitrogenous  organic  matter.  The 
nitrifying  process  is  now  believed  to  take  place  under  the  in- 
fluence of  minute  organisms,  and  the  process  goes  on  in  the  vari- 
ous soils  at  very  different  rates  according  to  the  alkalinity  of  the 
soil,  to  the  amount  of  moisture  and  to  other  conditions.  More- 
over, the  nitrates  once  formed  may  again  be  reduced  to  ammoni- 
acal  compounds,  or  even  to  free  nitrogen,  so  that  the  nitrates 
cannot  be  a  quantitative  indication  of  the  amount  of  pollution. 

In  spite  of  this,  Frankland  lays  great  stress  on  the  exact  deter- 
mination of  nitrogen  in  this  form,  and  has  introduced  into  water 
reports  the  term  "  previous  sewage  contamination."  The  figures 
given,  in  any  case,  under  this  head  are  reached  by  determining 
the  total  amount  of  nitrogen  which  is  present  as  ammonia,  and 
also  as  nitrites  and  nitrates ;  after  subtracting  the  small  amount 
of  nitrogen  which  rain  water  contains  in  these  forms,  there  is 
calculated  from  the  remainder  how  much  of  what  is  called  "  aver- 
age London  sewage "  would  be  necessary  to  account  for  this 
amount  of  nitrogen.  The  composition  of  the  so-called  "  average 
London  sewage"  is  not,  as  might  be  supposed,  deduced  from 
a  considerable  number  of  examinations  made  at  various  times, 
but  the  average  sewage  is  taken  arbitrarily  as  containing  10  parts 
of  combined  nitrogen  in  100,000  parts. 

Mallet  (in  a  report  already  cited)  is  "  inclined  to  attach  spe- 
cial and  very  great  importance  to  a  careful  determination  of  the 
nitrites  and  nitrates  in  water  to  be  used  for  drinking." 

It  is  true  that  in  consecutive  examinations  of  the  same  water 
it  is  satisfactory  to  know  exactly  the  amount  of  nitrates  and  the 
variation  from  time  to  time  ;  but,  in  case  of  a  single  examination, 
it  is  generally  sufficient  to  know  whether  there  is  much  or  little, 
or  none.  The  test  most  commonly  applied,  although  not  the 
most  delicate,  is  the  sulphate  of  iron  (ferrous  sulphate)  test.  A 
small  quantity  of  the  water  under  examination  is  mixed  in  a 
glass  tube  with  an  equal  volume  of  pure  concentrated  sulphuric 
acid.  The  mixture,  which  becomes  very  hot,  is  cooled  to  the 
temperature  of  the  air,  and  there  is  then  poured  upon  it  a  solu- 
tion of  sulphate  of  iron.  If  nitrates  are  present,  a  dark  ring  or 
layer  forms  between  the  two  liquids.  The  amount  of  nitrates 
present  may  be  inferred  from  the  extent  to  which  the  water 


36  WATER  SUPPLY. 

must  be  concentrated  before  it  will  give  indications  by  this  test, 
but  the  indications  are  strictly  comparable  only  when  the  test  is 
performed  in  precisely  the  same  way  and  by  the  same  person. 

It  should  be  understood  that  the  argument  drawn  from  the 
presence  of  nitrates  is  this :  The  nitrates  indicate  the  previous 
existence  of  nitrogenous  organic  matter,  which  has  been  oxidized 
and  converted  into  harmless  compounds  by  natural  agencies. 
If  these  same  agencies  could  be  relied  on  indefinitely  it  would  be 
well,  but  no  one  can  tell  at  what  moment — owing  to  increase  in 
the  amount  of  the  polluting  substances,  or  to  their  gradual  accu- 
mulation in  the  soil,  or  to  other  changed  conditions — the  natural 
agencies  may  prove  inadequate  to  the  task  and  allow  incom- 
pletely oxidized  and  harmful  substances  to  reach  the  source  of 
supply. 

Organic  matter. — Of  the  polluting  material  which  reaches 
water  which  may  be  used  for  drinking,  the  organic  portion  is  felt 
to  be  that  which  directly  or  indirectly  introduces  the  element  of 
danger.  Just  how  and  from  what  particular  substances  the  dan- 
ger arises  is  unknown,  and  it  is  extremely  doubtful  whether  the 
dangerous  something  will  ever  be  an  object  of  chemical  deter- 
mination, but  in  our  present  ignorance  it  is  generally  felt  that 
it  is  desirable  to  obtain  such  indications  as  are  possible  of  the 
amount  and  character  of  the  organic  matter  present. 

To  a  person  unfamiliar  with  chemistry,  it  might  seem  to  be 
no  difficult  task  to  determine  exactly  how  much  matter  of  animal 
and  how  much  matter  of  vegetable  origin  is  present  in  a  given 
water.  The  truth  is,  however,  that  it  is  not  only  difficult  but 
impossible,  either  to  determine  the  total  amount  of  organic  mat- 
ter or  to  decide  upon  its  origin.  As  far  as  the  total  amount  is 
concerned,  the  fact  that  it  cannot  be  determined  is  a  matter  of 
no  great  consequence.  Even  if  the  chemist  could  say  with  cer- 
tainty that  a  particular  water  contained  exactly  I  or  2  or  5  parts 
of  organic  matter  in  100,000,  we  should  be  far  from  having  the 
data  necessary  to  form  an  opinion  as  to  the  wholesomeness  of  the 
water,  for  it  is  evident  to  any  one  that  a  pound  of  sugar  or  of 
glycerine  would  have  a  very  different  importance  from  that  of  a 
pound  of  (dry)  faeces,  yet  either  is  a  pound  of  organic  matter. 

Formerly  it  was  the  general  custom  to  subject  the  residue  of 
evaporation  ("  total  dissolved  solids  ")  to  the  action  of  a  low  red 
heat  until  all  the  carbonaceous  matter  was  destroyed  and  to  deter- 


WATER  ANALYSIS.  37 

mine  the  loss  of  weight.  Thus  was  obtained  what  is  now  gen- 
erally tabulated  as  "loss  on  ignition,"  or  "  organic  and  volatile 
matter ; "  but  the  loss  of  weight  is  far  from  being  entirely  due  to 
the  destruction  of  organic  matter.  According  to  the  degree 
of  heat  applied  and  the  length  of  time  during  which  it  is  con- 
tinued, there  is  more  or  less  loss  due  to  the  volatilization  of 
alkaline  chlorides.  There  is  also  loss  from  the  decomposition 
and  partial  volatilization  of  several  compounds  ;  thus,  the  car- 
bonates of  lime  and  magnesia  are  more  or  less  completely  con- 
verted into  oxides  by  expulsion  of  the  carbonic  acid,  or  in  the 
presence  of  a  sufficient  quantity  o!  silicic  acid,  into  silicates.  The 
nitrates  are  converted  into  carbonates,  oxides,  or  silicates,  chlo- 
ride of  magnesium  is  decomposed  in  the  presence  of  hydrated 
compounds  with  escape  of  chlorhydric  acid,  and  other  changes 
take  place  which  it  is  not  necessary  to  particularize. 

For  these  reasons,  no  two  persons  are  likely  to  obtain  the 
same  result  from  the  same  water,  and  not  much  value  is  attached 
nowadays  to  the  determination  ;  it  is  sometimes  of  assistance  in 
forming  the  final  opinion  in  case  of  a  doubtful  water,  but  the  way 
in  which  the  residue  acts  when  heated  gives  more  information 
than  a  knowledge  of  the  loss  of  weight. 

Of  the  more  modern  methods  in  somewhat  general  use  for 
reaching  information  about  the  organic  matter  in  water,  there 
are  three  which  may  be  mentioned  here,  and  which  will  be  spoken 
of  as  the  "  permanganate  "  method,  the  "  ammonia  "  process,  and 
"  Frankland's  "  method.*  All  of  the  processes  possess  a  certain 
value,  and  all  are  widely  open  to  criticism. 

Permanganate  of  potash  is  a  highly  colored  crystalline  salt 
soluble  in  water,  to  which,  even  if  the  solution  be  very  dilute,  it 
communicates  a  marked  pink  color.  This  compound,  which 
contains  a  considerable  proportion  of  oxygen,  possesses  the 
property  of  oxidizing,  with  more  or  less  readiness,  most  forms  of 
organic  matter,  being  itself  destroyed  in  the  process  and  losing 
the  characteristic  color.  By  successive  additions  of  a  perman- 

*  These  various  processes  will  be  discussed  only  briefly  in  this  place.  They 
have  recently  been  thoroughly  investigated  by  Professor  J.  W.  Mallet,  under  direc- 
tion of  the  National  Board  of  Health.  The  full  report  has  not  yet  appeared,  but  a 
preliminary  report  was  published  as  a  Supplement  (No.  19)  to  the  National  Board  of 
Health  Bulletin,  May  27,  1882. 


38  WATER   SUPPLY. 

ganate  solution  of  known  strength  until  the  color  persists,  it 
is  possible  to  determine  how  much  permanganate  is  destroyed 
by  a  known  volume  of  a  given  water.  There  are  various  ways 
of  applying  the  permanganate  solution.  Some  prefer  to  use  the 
reagent  in  alkaline,  and  others  in  acid  solutions ;  some  heat  the 
liquid  to  one  temperature  and  some  to  another.*  The  results 
obtained  are  reported  by  stating  how  many  parts,  by  weight,  of 
the  crystallized  permanganate  are  required  for  100,000  parts  by 
weight  of  water ;  or  how  many  parts,  by  weight,  of  oxygen  (from 
the  permanganate)  are  used  up  in  the  process.  Some,  indeed, 
assume  an  arbitrary  number,  by  which  they  multiply  the  amount 
of  permanganate  employed,  and  call  the  result  organic  matter. 
Where  the  expression  "  organic  matter "  occurs  in  German  re- 
ports, the  figures  are  probably  obtained  by  multiplying  the 
amount  of  oxygen  used  up  by  2O,f  but  in  American  reports  the 
expression  is  quite  likely  to  mean  simply  the  "  loss  on  ignition." 
The  results  of  the  permanganate  method  cannot  have  an  absolute 
value,  because  different  organic  substances  vary  in  the  complete- 
ness with  which  they  are  oxidized  under  the  same  conditions; 
and,  even  if  they  were  all  completely  oxidized  under  certain 
attainable  conditions,  it  would  still  be  true  that  one  gram  of  one 
kind  of  organic  matter  would  require  a  very  different  amount  of 
oxygen  from  that  which  would  be  required  by  one  gram  of  some 
other  kind  of  organic  matter.  Moreover,  with  the  same  water, 
the  results  differ  very  much  according  to  the  method  of  employ- 
ing the  test,  so  that  to  be  able  to  give  a  useful  interpretation  to 
any  particular  results,  it  is  necessary  to  know  what  method  was 
followed  by  the  analyst. 

The  so-called  ammonia  method  of  water  analysis  was  devised 
by  the  English  chemists  Chapman,  Wanklyn  and  Smith,  J  and 
has  been  much  used  in  England  and  in  this  country.  In  this 


*  See  Kubel's  Anleitung  zur  Untersuchung  von  Wasser,  bearbeitet  von  Dr.  Ferd. 
Tiemann,  Braunschweig,  1874.  Also  a  paper  by  Dr.  Tidy,  Chemical  News,  xxxvii 
(1878),  p.  283. 

f  Or  by  multiplying  the  amount  of  permanganate  consumed  by  5.  This  is  accord- 
ing to  Dr.  Woods,  but  Dr.  Letheby  prefers  to  multiply  the  amount  of  permanganate 
by  8.  Whatever  number  be  used,  it  frequently  happens  that  the  "organic  matter," 
as  thus  estimated,  exceeds  the  weight  of  the  "  total  dissolved  solids." 

\  Water  Analysis.  By  J.  A.  Wanklyn  and  E.  T.  Chapman.  5th  edition, 
rewritten  by  J.  A.  Wanklyn,  London,  1879. 


WATER  ANALYSIS.  39 

method,  advantage  is  taken  of  the  fact  that  certain  kinds  of  ni- 
trogenous organic  matter,  when  treated  with  a  strongly  alkaline 
solution  of  permanganate  of  potash,  give  off  a  definite  portion  or 
the  whole  of  their  nitrogen  as  ammonia;  and  the  value  of  the 
method  lies  in  the  assumption  that  it  is  the  nitrogenized  organic 
matter  which  is  to  be  regarded  as  the  chief  source  of  danger  in 
polluted  water.  In  working  the  ammonia  method,  the  water 
under  examination  is  put  into  a  retort,  made  alkaline  by  means 
of  carbonate  of  soda,  and  distilled  as  long  as  the  water  which 
condenses  contains  enough  ammonia  to  be  measured  by  Nessler's 
solution.  Then  a  solution  of  caustic  soda  and  permanganate  of 
potash  is  added,  and  distillation  is  continued.  Another  portion 
of  ammonia  now  comes  off,  owing  to  the  action  of  the  perman- 
ganate on  the  nitrogenous  organic  matter.  The  amount  of 
ammonia  thus  obtained  is  determined,  and  is  tabulated  as  "al- 
buminoid ammonia,"  because  albumin  is  one  of  the  bodies  which 
acts  in  this  way. 

It  will  thus  be  understood  that  the  so-called  "albuminoid 
ammonia "  is  not  something  which  exists  in  the  water  ready 
formed  ;  moreover,  because  different  amounts  are  obtained  from 
the  same  weight  of  different  nitrogenous  substances,  as  well  as 
on  account  of  the  fact  already  alluded  to,  that  the  oxidation  of 
different  substances  by  the  permanganate  of  potash  is  more  or 
less  incomplete,  the  figures  obtained  have  a  relative  rather  than 
an  absolute  significance. 

Although  this  method  does  not  accomplish  all  that  might  be 
desired,  the  results,  properly  interpreted,  are  of  great  value,  and 
the  method  has  been  of  immense  service  in  the  cause  of  public 
health. 

The  third  method,  known  as  the  "combustion"  process,  or 
Frankland's  method,  was  devised  by  Frankland  and  Armstrong, 
and  used  by  the  Rivers  Pollution  Commission  of  Great  Britain 
in  the  examination  of  the  very  large  number  of  waters,  the  anal- 
yses of  which  appear  in  the  various  reports  of  the  Commission. 
This  method  is  by  far  the  most  elaborate  of  any  that  have  been 
proposed :  it  consists  in  evaporating  a  given  quantity  of-  the 
water,  under  carefully  regulated  conditions,  and  in  submitting 
the  residue  to  a  process  of  organic  analysis,  by  which  all  the 
carbon  is  converted  into  carbonic  acid  and  the  nitrogen  is  liber- 
ated in  the  gaseous  state.  The  mixture  of  nitrogen  and  carbonic 


4°  WATER  SUPPLY. 

acid  is  then  analyzed  by  processes  of  gas  analysis.  The  results 
are  stated  in  so  many  parts  of  "  organic  carbon  "  and  so  much 
"  organic  nitrogen,"  in  100,000  parts  of  the  water,  and  sometimes 
the  sum  of  the  two  is  spoken  of  as  the  amount  of  the  "  organic 
elements."  The  character  of  the  organic  matter  is  inferred  from 
the  relative  proportion  of  carbon  and  nitrogen. 

The  process,  as  Frankland  himself  says,  is  "  both  troublesome 
and  tedious."  The  apparatus  employed  is  frangible  and  some- 
what costly,  and  the  manipulative  skill  of  a  trained  chemist  is 
required  to  carry  out  the  work.  It  is  moreover  a  process  that 
cannot  be  taken  up  off-hand,  even  by  a  trained  chemist,  but  one 
requiring  tolerably  constant  practice.  As  Mallet  says:  "It  is 
better  adapted  to  regular  use  in  the  examination  of  many 
samples  of  water  in  a  large  public  laboratory  than  to  occasional 
use  by  a  private  individual  in  now  and  then  examining  a  single 
water." 

Although  the  combustion  process  is  the  most  elaborate,  and, 
in  some  respects  the  most  satisfactory  that  we  have,  even  this, 
"in  its  present  form  cannot  be  considered  as  '  determining'  the 
carbon  and  nitrogen  of  the  organic  matter  in  water  in  a  sense  to 
justify  the  claim  of  '  absolute  '  value  for  its  results  which  has 
been  denied  to  those  of  all  other  methods.  It  is  but  a  method 
of  approximation,  involving  sundry  errors,  and  in  part  a  balance 
of  errors."  * 

Standards  of  purity. — Having  followed  this  brief  description 
the  methods  of  analysis  most  frequently  employed,  a  person, 
who  is  not  a  chemist,  may  naturally  ask  for  some  directions  in 
order  to  interpret  the  figures  reported  by  the  analyst.  Now,  it 
is  true  that  it  may  be  possible  to  fix  certain  numerical  limits 
and  to  reject  without  hesitation  all  waters  exceeding  these 
limits ;  but  there  always  will  be  difficulty  in  deciding  how  near 
to  any  limit  a  suspicious  water  may  come  and  still  be  used  with 
a  reasonable  degree  of  safety.  To  condemn  a  water  without 
sufficient  cause  is,  of  course,  undesirable,  as  the  procuring  a  dif- 
ferent supply  may  involve  considerable  expense. 

Moreover,  it  cannot  be  insisted  upon  too  strongly  that  differ- 
ent classes  of  water  cannot  be  judged  by  the  same  standard,  and 


*  For  a  full  discussion  of  the  sources  of  error,  see  Mallet's  report,  already  alluded 
to  ;  also,  Amer.  Chem.  Journ.,  iv  (1883). 


WATER  ANALYSIS.  41 

the  results  of  the  analysis  of  waters  belonging  to  different  classes 
ought  not  to  be  put  into  the  same  table  or  otherwise  arranged  so 
as  to  invite  comparison.  If  within  the  same  geological  area  it  is 
possible  to  analyze  the  water  from  a  considerable  number  of  un- 
polluted wells,  a  standard  may  be  fixed  for  the  well  water  of  that 
region,  and  a  surface  water  may  be  compared  with  other  surface 
waters  of  the  same  or  of  a  similarly  situated  region  ;  or  a  stream  in 
one  part  of  its  course  may  be  compared  with  its  own  unpolluted 
head  waters.  To  fix,  however,  a  definite  standard  which  will 
apply  to  all  waters  and  by  which  any  one  can  judge  of  a  given 
water  from  the  numerical  results  of  analysis  is  impracticable. 
Every  doubtful  water  must  be  considered  by  itself  with  all  the 
light  that  can  be  brought  to  bear  upon  it. 

Bearing  in  mind  what  has  just  been  said,  we  may  note  the  in- 
terpretation which  is  given  to  the  results  of  the  several  methods 
in  common  use  for  determining  "  organic  matter,"  or,  at  least, 
for  obtaining  indications  as  to  its  amount  and  character.  Wan- 
klyn's  own  interpretation  of  the  results  of  the  ammonia  process 
is  essentially  as  follows : 

If  a  water  yield  no  "  albuminoid  ammonia,"  it  may  be  passed 
as  organically  pure,  despite  of  much  free  ammonia  and  chlorides ; 
a  water  giving  less  than  0.005  Part  °f  "  albuminoid  ammonia  " 
in  100,000  parts  may  be  regarded  as  very  pure.  A  water  contain- 
ing 0.005  Part  °f  "  albuminoid  ammonia  "  together  with  a  con- 
siderable quantity  of  free  ammonia  is  suspicious,  but  in  the 
absence  of  free  ammonia,  the  "albuminoid  ammonia"  maybe 
allowed  to  amount  to  something  like  o.oio  part  ;  above  o.oio 
should  be  regarded  as  very  suspicious,  and  according  to  Wanklyn 
over  0.015  part  should  condemn  the  water. 

The  Rivers  Pollution  Commission,  in  interpreting  the  results 
of  Frankland's  process,  make  the  following  classification  :  "  Sur- 
face water  or  river  water  which  contains  in  100,000  parts  more 
than  0.2  part  of  organic  carbon  or  0.03  part  of  organic  nitrogen 
is  not  desirable  for  domestic  supply,  and  ought,  whenever  practi- 
cable, to  be  rejected.  Spring  and  deep-well  water  ought  not  to 
contain  in  100,000  parts  more  than  o.i  part  of  organic  carbon  or 
0.03  part  of  organic  nitrogen." 

Dr.  Frankland,  while  "  deprecating  a  hard  and  fast  division 
of  water  into  classes,"  suggests  a  rough  classification  according 
to  the  amount  of  organic  carbon  present ;  this  classification  is 


42  WATER  SUPPLY. 

given  in  Table  III,  the  figures  indicating  such  a  fraction  of  one 
part  by  weight  of  organic  carbon  in  100,000  parts  by  weight  of 
the  water. 

Dr.  Tidy,  while  admitting  the  impossibility  of  deciding  of  the 
quality  of  a  water  from  an  incomplete  analysis  suggests  certain 
limits  as  a  guide  to  the  interpretation  of  the  results  obtained  by 
the  permanganate  process,  conducted,  be  it  understood,  accord- 
ing to  a  particular  method.  These  also  appear  in  Table  III. 

TABLE  III.— CLASSIFICATION  OF  NATURAL  WATERS. 

Parts  in  100,000. 


CLASSIFICATION. 

ORGANIC  < 
DR.  FRA 

Upland  sur- 
face water. 

CARBON.— 
NKLAND. 

Other 
waters. 

OXYGEN  REQUIRED  TO  OXI- 
DIZE ORGANIC  MATTER.  — 
DR.  TIDY. 

I  Water  of  great  organic  purity  . 
II  \Vater  of  medium  purity  

O.    -O.2 
0.2-0-4 

o  .  4-0  .  6 
0.6  + 

O.-O.I 
0.1-0.2 

0.2-0.4 
0.4  + 

o.     -o  05 

0.05-0.15 
O.I5-0.2I 
O.2I  + 

Ill  Water  of  doubtful  purity 

IV  Impure  water 

Some  of  the  limiting  amounts  which  have  been  suggested  by 
other  chemists  are  given  in  Table  IV  : 


TABLE  IV. — STANDARDS  OF  PURITY. 

Parts  in  100,000. 


TOTAL 
SOLIDS. 

ORGANIC 

MATTER. 

NITRIC  ACID 

(N206). 

CHLORINE. 

TOTAL 
HARDNESS. 

Reichardt       .  .       .  .      .  . 

CQ 

2 

O   4. 

O  2—  O  8 

18 

Kubel  and  Tiemann  .... 
Wibel 

50 

CQ 

5- 

0.5-1-5 

Or    2 

2-3 

3C 

18-20 

1  8  °o 

Fischer  

CQ 

2    7 

-3   e 

17 

4. 

Professor  Mallet,  in  the  report  already  alluded  to,  after  record- 
ing the  results  of  an  examination  into  the  various  processes  of 
analysis  which  have  been  briefly  described,  draws  certain  general 
conclusions  as  follows : 

"i.  It  is  not  possible  to  decide  absolutely  upon  the  whole- 
someness  or  unwholesomeness  of  a  drinking  water  by  the  mere 
use  of  any  of  the  processes  examined  for  the  estimation  of 
organic  matter,  or  its  constituents. 

"  2.  I  would  even  go  further,  and  say  that,  in  judging  the 
sanitary  character  of  a  water,  not  only  must  such  processes  be 
used  in  connection  with  the  investigation  of  other  evidence  of  a 


WATER   ANALYSIS.  43 

more  general  sort,  as  to  the  source  and  history  of  the  water,  but 
should  even  be  deemed  of  secondary  importance  in  weighing  the 
reasons  for  accepting  or  rejecting  a  water  not  manifestly  unfit 
for  drinking  on  other  grounds. 

"  3.  There  are  no  sound  grounds  on  which  to  establish  such 
general  '  standards  of  purity '  as  have  been  proposed,  looking 
to  exact  amounts  of  organic  carbon  or  nitrogen,  '  albuminoid 
ammpnia/  oxygen  of  permanganate  consumed,  etc.,  as  permis- 
sible or  not.  Distinctions  drawn  by  the  application  of  such 
standards  are  arbitrary,  and  may  be  misleading. 

"4.  Two  entirely  legitimate  directions  seem  to  be  open  for 
the  useful  examination  by  chemical  means  of  the  organic  con- 
stituents of  drinking  water,  namely,  first,  the  detection  of  very 
gross  pollution,  such  as  the  contamination  of  the  water  of  a  well 
by  accidental  bursting  or  crushing  of  soil-pipes,  extensive  leakage 
of  drains,  etc.,  and  secondly,  the  periodical  examination  of  a 
water  supply,  as  of  a  great  city,  in  order  that,  the  normal  or 
usual  character  of  the  water  having  been  previously  ascertained, 
any  suspicious  changes  which  from  time  to  time  may  occur  shall 
be  promptly  detected  and  their  cause  investigated. 

"  5.  In  connection  with  this  latter  application  of  water  analy- 
sis, there  seems  to  be  no  objection  to  the  establishment  of  local 
'  standards  of  purity'  for  drinking  water,  based  on  sufficiently 
thorough  examination  of  the  water  supply  in  its  usual  con- 
dition." 

These  conclusions  are  given,  as  they  coincide  almost  exactly 
with  what  the  author  has  frequently  had  occasion  to  assert,  and 
has  for  years  tried  to  teach.  "  In  the  majority  of  cases,  chemical 
examination  alone  cannot  be  relied  upon  as  giving  conclusive 
evidence  as  to  the  suitability  of  a  water  for  drinking.  Of  course, 
if  a  water  is  hard,  the  chemist  can  say,  without  hesitation,  that 
the  water  is  unsuited  for  supply  on  account  of  its  probable  effect 
on  steam  boilers,  and  because  it  will  be  uneconomical  for  use  in 
washing.  If  the  water  contains  arsenic  or  lead  or  other  poison- 
ous metal,  the  chemist  can  discover  it.  If  the  water  is  grossly 
polluted,  or  is  of  exceptional  purity,  chemical  examination  can 
determine  these  facts  ;  but,  in  a  vast  majority  of  cases,  while 
chemistry  may  teach  something  and  aid  in  the  decision,  it  cannot 
teach  everything,  and  it  cannot  decide.  Now,  it  would  be  very 
convenient,  if  it  were  possible,  to  take  each  item  which  is  made 


44  WATER   SUPPLY. 

the  object  of  analytical  determination,  and  say  that  a  good  water 
may  contain  so  much,  and  if  a  water  contains  more,  it  i?  not 
good.  This  is  impossible :  a  certain  amount  of  the  same  sub- 
stance might  in  one  case  be  a  sign  of  fearful  contamination,  while 
in  another  it  might  indicate  only  a  normal  constituent  of  the 
water. 

"  In  view  of  the  impossibility  of  saying  exactly  what  is  and 
what  is  not  harmful,  any  considerable  departure  from  the  normal 
character  of  the  water  in  a  given  locality  should  be  regarded  with 
suspicion.  It  is  true  that  various  students  of  the  matter  of  water 
supply  have  formulated  '  standards '  which  a  water  may  not 
overpass.  They  are,  however,  only  of  relative  value."  * 

It  should  not  be  inferred  that  the  chemical  analysis  is  value- 
less because  it  cannot  furnish  data  for  absolute  decision,  but  it  is 
a  great  mistake  to  suppose  that  the  proper  way  to  consult  a 
chemist  is  to  send  a  sample  of  water  in  a  sealed  vessel  with  no 
hint  as  to  its  source.  On  the  contrary,  the  chemist  should  know 
as  much  as  possible  as  to  the  history  and  source  of  the  water,  and 
if  possible  should  take  the  samples  himself — that  is  if  he  is  to  ex- 
press an  opinion  as  to  the  suitableness  of  the  water  for  drinking. 
Nor  is  it  sufficient  that  some  other  competent  person  should 
possess  the  knowledge  of  the  locality,  etc.,  and  endeavor  to  in- 
terpret the  figures  furnished  by  the  chemist.  There  are  many 
things  which  guide  the  chemist  that  he  cannot  put  into  numer- 
ical results  or  even  on  to  paper  at  all.  Many  observations  are 
made  in  the  course  of  an  analysis  by  an  experienced  person,  of 
which  he  is  himself  hardly  conscious,  but  which  aid  in  making  up 
the  final  opinion.  Foxf  very  truly  says : 

"It  is  a  golden  rule  in  water  analysis  never  to  give  an  opinion 
unless  the  analyst  knows  (i)  the  nature  of  the  source  of  a  water— 
whether  it  comes  from  a  spring  or  well  or  river  or  rain  reservoir, 
etc.;  (2)  the  depth  of  the  well,  if  it  is  withdrawn  from  one  ;  (3) 
the  geology  of  the  district  from  which  it  is  derived,  together  with 
the  character  of  the  soil  and  subsoil ;  (4)  the  distance  from  the 
source  of  the  water  of  the  nearest  filth  or  drain." 

At  the  present  time,  chemical  examination,  in  connection 
with  a  thorough  knowledge  of  a  proposed  source  of  supply,  must 


*  Buck's  Hygiene,  Vol.  i,  p.  303. 

f  Sanitary  Examination  of  Water,  Air  and  Food.     London,  1878. 


WATER  ANALYSIS.  45 

be  the  main  guide  in  the  selection  or  rejection  of  a  water ;  but 
there  is  reason  to  hope  that-  eventually  the  decision  may  be 
thrown  largely  upon  the  biologist.  Investigations  have  been  made 
from  a  biological  stand-point  in  two  directions:  (i)  by  an  exam- 
ination of  the  organisms  in  the  water  itself  or  which  develop  in 
it  when  the  water  is  allowed  to  stand ;  (2)  by  injecting  the  concen- 
trated water,  or  a  solution  of  the  residue  of  evaporation,  under 
the  skin  of  rabbits  or  other  animals,  and  observing  the  effect  on 
the  temperature,  etc.,  of  the  animals  experimented  upon. 

With  reference  to  the  first  method,  it  may  be  said  that  a 
microscopical  examination  of  the  suspended  and  sedimentary 
matter  should  always  accompany  the  chemical  examination,  and 
there  is  no  difficulty  in  recognizing  grains  of  starch,  fibers  of 
cotton,  silk,  wool,  etc.,  and  many  other  sorts  of  animal  and 
vegetable  debris  if  present ;  of  course,  substances  like  those  men- 
tioned are  evidence  of  more  or  less  contamination.  With  regard 
to  living  organisms,  we  do  not  know  as  much  as  we  have  a  right 
to  hope  to  know  about  their  connection  with  the  wholesomeness 
of  a  water.  It  may  be  said,  in  a  general  way,  that  bacteria  occur- 
ring in  considerable  numbers  are  a  sign  of  impure  water,  as  are 
also  certain  infusoria,  such  asparamecium,  vorticella,  monas,  etc. 
The  occurrence  of  leptothrix,  crenothrix,  etc.,  are  also  suspicious 
signs,  but  the  diatoms  and  the  green  algae,  as  a  rule,  do  not  indi- 
cate impurity,  and  are,  generally  speaking,  harmless  unless  suffi- 
cient numbers  are  present  to  affect  the  water  by  their  death  and 
decay.  (See  also  Chapter  IV. — Surface  water  as  a  source  of 
supply.) 

The  second  method  of  biological  investigation  was  proposed 
by  Emmerich,*  who  says:  "If  the  water  under  examination,  or 
the  aqueous  extract  (of  the  residue),  to  the  bulk  of  40-80  c.c.  be  in- 
jected subcutaneously  into  a  full-grown  rabbit,  and  fail  to  produce 
a  continued  elevation  of  temperature  of  more  than  IQ  C.,  followed 
by  death,  then  the  water  contains  no  putrid  substances  dangerous 
to  health,  or  contains  them  in  so  small  an  amount  that  they  are 
not  worth  considering."  He  further  suggests,  that  the  amount 
of  such  dangerous  substances  may  be  estimated  from  the  amount 
of  water  which  must  be  evaporated  in  order  to  obtain  an  extract 
which  will  produce  in  animals  the  effects  which  he  describes. 

*  Zeilschrift  fur  Biologic,  xiv  (1878),  563-603. 


^  WATER  SUPPLY. 

Something  has  been  done  in  this  same  direction  by  Dr.  George 
M.  Sternberg,  U.  S.  A.,  *  in  connection  with  his  investigation  of 
malarial  fever,  and  also  by  Prof.  H.  Newell  Martin,  of  the  Johns 
Hopkins  University,  in  connection  with  Prof.  Mallet's  investi- 
gation into  the  different  methods  for  the  analysis  of  drinking 
waters.  Whatever  may  develop  in  the  future  from  this  method 
of  research,  it  is  certain  that  it  has  not  yet  become  a  method  on 
which  we  can  rely,  and  that  Emmerich's  statement  is  altogether 
too  sweeping. 

In  this  connection  should  also  be  mentioned  the  proposal  by 
Koch  f  to  examine  the  water  by  means  of  culture  experiments 
in  gelatine  with  subsequent  microscopic  examination ;  but  this 
method,  like  the  preceding,  is  at  present  simply  developing.  A 
somewhat  similar  method  of  experimenting  has,  for  a  longer  time, 
been  occasionally  employed.  It  consists  in  carefully  collecting 
some  of  the  water  in  flasks  that  have  previously  been  sterilized 
by  heat  and  introducing  a  small  quantity  into  each  of  several 
test-tubes  containing  some  freshly  boiled  Pasteur's  solution,  so- 
called.  This  solution  is  particularly  favorable  to  the  growth  of 
"  bacteria,"  if  any  such  or  their  germs  are  in  the  water.  The 
tubes  are  plugged  with  cotton-wool,  and  an  attempt  is  made  to 
estimate  the  amount  of  impurity  in  the  water  from  the  degree  of 
turbidity  produced  in  a  given  time.  None  of  these  methods  have 
yet  reached  the  stage  of  practical  utility,  and  it  must  be  left  en- 
tirely with  the  specialists  to  interpret  the  results  of  their  own 
observations. 

Popular  tests. — The  writer  has  little  sympathy  with  popular 
tests.  It  is  true  that  the  observations  on  odor  and  taste  and 
color  may  be  made  by  a  person  who  is  not  a  chemist  ;  there  are 
also  certain  qualitative  tests  that  any  intelligent  person  can  learn 
to  make  satisfactorily,  and  which  would  serve  as  indications  to 
the  chemist.  It  is,  in  general,  true  of  popular  tests,  that  they 
are  apt  to  lead  either  to  an  unjustified  sense  of  security  or  to  an 
unnecessary  feeling  of  alarm.  The  following  test  for  sewage 
contamination,  proposed  by  Heisch,  and  recommended  by  others, 
has  some  value  : 

Put  some  of  the  water — say  half  a  pint — into  a  clean,  colorless, 

*  Supp.  No.  14,  Bulletin  National  Board  of  Health,  July  23,  1881. 
f  Mittheilungen  aus  dam  kaiserlichen  Gesundheitsamte.     I    Band,  Berlin,  1881, 
page  36.     See  also  a  paper  by  Angus  Smith,  in  The  Sanitary  Record,  February,  1882. 


WATER  ANALYSIS.  47 

glass-stoppered  bottle,  add  a  few  grains  of  white  sugar,  shake 
until  the  sugar  has  dissolved,  and  leave  the  bottle  freely  exposed 
to  the  light  in  a  warm  room  for  a  week  or  ten  days.  If  the 
water  becomes  turbid,  it  is  open  to  suspicion  of  sewage  contam- 
ination ;  if  it  remains  clear  it  is  probably  safe. 

Collection  of  samples. — In  connection  with  the  chemical  exam- 
ination of  water,  the  importance  of  taking  due  care  in  the  collec- 
tion of  samples  may  be  alluded  to.  The  best  vessel  for  collecting 
water  for  analysis  is  a  glass-stoppered  bottle  ;  a  clean  demijohn 
which  has  never  been  used  for  any  other  purpose  and  which  is 
stopped  with  a  new  and  clean  cork  answers  perfectly  well  and 
is  often  more  convenient.  Tin  cans  or  stoneware  jugs  are  not 
suitable. 

Considerable  care  is  necessary  in  order  to  get  a  fair  sample  of 
the  water.  The  demijohn  should  be  rinsed  several  times  thor- 
oughly with  the  water  to  be  collected  and  finally  filled  not  quite 
to  the  mouth.  The  cork  should  be  washed  with  the  same  water 
and  the  demijohn  stoppered  tightly.  The  stopper  should  be 
tied  over  with  a  piece  of  cloth  or  "  bandage  gum,"  and  the  string 
sealed  with  sealing  wax,  that  the  water  may  not  be  tampered 
with  in  transit. 

If  the  water  is  taken  from  a  pump  or  from  a  faucet,  enough 
water  should  be  pumped  or  allowed  to  run  to  waste  to  thor- 
oughly clear  the  pipes.  In  taking  water  from  a  pond  or  river 
it  will  generally  be  most  convenient  to  use  a  clean  crockery 
pitcher,  which  may  be  filled  by  plunging  it  beneath  the  surface 
(so  as  to  avoid  any  scum  or  floating  material)  and  then  emptied 
into  the  demijohn;  or  a  new  and  clean  tin  dipper  may  be 
employed.  If  a  glass  bottle  is  used,  it  may  be  plunged  directly 
into  the  water  and  thus  filled.  In  taking  water  from  a  river,  the 
middle  of  the  stream  should  be  chosen  if  only  one  sample  is 
taken. 


CHAPTER   III. 

RAIN  WATER  AS  A   SOURCE   OF   SUPPLY. 

THE  collection  of  the  rain  directly  as  a  source  of  public  sup- 
ply, in  our  latitude,  would  be  undertaken  only  under  very  excep- 
tional circumstances.  In  many  localities,  however,  where  there 
is  no  sufficient  public  supply  and  where  wells  are  out  of  the 
question,  the  collection  of  rain  water  by  the  individual  house- 
holder becomes  a  necessity  ;  also  in  cases  where  the  public  supply 
is  hard  and  unfit  for  washing.  A  house  covering  an  area  of  40  by 
20  feet,  or  800  square  feet,  would  receive  upon  its  roof,  with  a 
rainfall  of  42  inches,  2,800  cubic  feet  of  water  in  the  course  of 
the  year.  If  three-quarters  of  this  could  be  collected,  it  would 
furnish  a  supply  of  something  over  40  gallons  per  day,  on  the 
average. 

The  rain  which  falls,  even  in  the  open  country,  is  far  from 
being  pure  in  the  chemical  sense,  as  it  washes  from  the  air  both 
gaseous  and  solid  substances.  The  Rivers  Pollution  Commission 
of  Great  Britain  obtained  the  following  average  results  from  the 
examination  of  73  samples  of  rain  water,  all  but  two  of  which 
were  collected  at  the  experimental  farm  of  Messrs.  Lawes  and 
Gilbert,  Rothamsted,  England : 

Total  dissolved  solids 3-95  parts  in  100,000. 

Organic  carbon 0.099 

Organic  nitrogen O.O22 

Ammonia o .  050 

Nitrogen  as  nitrites  and  nitrates 0.007 

Total  combined  nitrogen 0.071 

Chlorine o. 63 

In  manufacturing  localities,  the  air,  and  consequently  the 
rain,  may  contain  much  impurity ;  and,  in  any  event,  when  the 
rain  is  collected  near  habitations  the  impurity  is  considerable. 
The  excrement  of  birds,  the  dead  bodies  of  insects,  leaves  from 
the  trees,  and  various  sorts  of  dust  and  dirt  lodge  on  the  roofs 
and  are  washed  off,  mainly  by  the  first  portions  of  the  rain. 


RAIN  WATER  AS  A   SOURCE   OF  SUPPLY.  49 

Devices,  some  of  them  automatic,  have  been  invented,  by  which 
the  first  portions  of  the  rain  are  allowed  to  go  to  wa^te,  but  they 
have  not  come  into  general  use.  Besides  the  sources  of  impurity 
to  which  rain  water  is  naturally  and  unavoidably  liable,  there  are 
accidental  sources  of-  contamination :  thus,  instances  have  been 
known  where  servants  have  emptied  the  house  slops  from  the 
upper  stories  on  to  the  roof,  thence  to  find  their  way  into  the 
cisterns.  It  is  to  be  hoped  that  such  instances  as  this  are  ex- 
tremely rare. 

The  proper  storage  of  rain  water  is  as  important  as  its  col- 
lection. For  the  storage  of  water  in  small  quantity  there  is 
nothing  better,  from  a  sanitary  point  of  view,  than  slate  tanks ; 
iron  tanks  protected  from  rusting  by  a  coating  of  coal-tar  paint 
are  also  unobjectionable.  Tanks  situated  at  the  top  of  the 
house  are  sometimes  in  direct  communication  with  the  drains 
by  means  of  the  overflow  pipes,  and  in  some  cases  it  has  been 
thought  that  the  water  has  been  rendered  impure  and  injurious 
to  health  by  gases  from  the  soil-pipes.  Any  mode  of  construc- 
tion which  admits  the  possibility  of  such  communication  is 
faulty.  Rain  water  is  generally  stored  in  underground  cisterns 
built  of  brick  and  cement,  and  acquires  a  slight  hardness  by 
dissolving  lime  from  the  cement,  especially  when  the  cistern  is 
new.  The  overflows  from  such  cisterns  should  be  constructed 
so  as  to  preclude  all  possibility  of  contamination  from  the  liquids 
or  gases  of  drains  or  sewers.  In  some  localities  wood  is  used 
for  the  construction  of  the  rain-water  tanks ;  thus  in  New 
Orleans,  according  to  Dr.  Smart, *  the  cisterns  are  constructed 
of  cypress  wood,  and  vary  in  capacity  from  500  to  60,000  gallons. 
"The  usual  capacity  of  the  dwelling-house  cistern  is  about  two 
thousand  gallons.  They  are  raised  a  few  feet  from  the  ground, 
and  their  contents  are  protected  by  a  lid  or  cover.  Some  are 
placed  under  the  shade  of  a  balcony  ;  a  few  have  a  special  roof 
over  them  ;  but  the  majority  have  only  such  protection  from  the 
rays  of  the  sun  as  is  afforded  by  their  position  against  the  house 
wall.  Many,  especially  in  the  older  parts  of  the  city,  are  situated 
in  unventilated  inclosures  which  are  rank  with  the  emanations 
from  unclean  privies." 


*  Report   on   the   Water  Supply  of  New   Orleans  and  Mobile.     Bull.  National 
Board  of  Health,  April  17,  1880. 
4 


50  WATER  SUPPLY. 

On  account  of  the  sediment  which  accumulates  in  the  cisterns 
in  which  rain  water  is  stored,  it  is  desirable  that  such  cisterns 
should  be  thoroughly  cleansed  from  time  to  time,  and  that  the 
water  should  be  filtered  before  being  used  for  drinking  or  for 
culinary  purposes.  The  matter  of  filtration  will  be  discussed  in 
a  subsequent  chapter  (page  151).  Dr.  Smart  examined  a  number 
of  cisterns  in  New  Orleans  which  had  not  been  cleaned  in  many 
years,  and  found  that  the  rate  of  deposit  was,  on  the  average, 
about  an  inch  a  year.  After  a  few  days'  repose,  the  sediment 
carried  in  by  the  rain  has  settled  to  the  bottom  and  the  water 
has  become  clear,  "  but  every  succeeding  rainfall  not  only  in- 
creases the  quantity  of  this  sediment,  but,  by  its  inflow,  stirs  up 
that  which  has  already  accumulated,  rendering  the  water  impure 
until  sedimentation  is  again  accomplished.  As  time  passes  the 
sediment  increases,  and  the  water  becomes  unfit  for  use  after 
each  rainfall.  These  conditions  are  aggravated  in  the  dry  season, 
when  the  water  is  low  in  the  cistern  and  the  quantity  of  sedi- 
ment is  relatively  much  increased." 

Underground  cisterns,  being  out  of  sight  and  consequently 
too  often  out  of  mind,  are  not  only  liable  to  be  neglected  and 
allowed  to  go  uncleaned  for  a  long  time,  but  are  also  liable  to 
become  leaky  and  thus  to  allow  of  the  contamination  of  the 
water  by  soakage  from  the  soil.  Dr.  Smart,  in  his  investigation 
of  the  water  supply  of  Memphis,  examined  a  considerable  num- 
ber of  the  4,000  cisterns  said  to  be  in  use.  He  found — 

Undoubtedly  sound 163 

Probably  sound 82 

Probably  siping 94 

Undoubtedly  leaky 190 

Total  number  examined 529 

Examination  of  Cistern   Water. 

It  is  often  very  difficult  to  decide,  by  chemical  examination, 
whether  a  cistern  water  is  to  be  regarded  as  fit  to  drink  or  not. 
Gross  pollution  can  be  easily  detected,  but,  as  the  presence  of 
more  or  less  organic  matter  is  a  necessary  consequence  of  the 
mode  of  collecting  the  water,  it  is  impossible  to  say  just  how 
much  is  permissible,  and  where  the  line  should  be  drawn.  The 
most  valuable  indications  are  afforded  by  the  chlorine,  which 


RAIN   WATER  AS  A   SOURCE   OF   SUPPLY.  51 

should  be  present  only  in  trifling  quantity,  as  a  rule,  not  over 
0.5  part  in  100,000,  except  near  the  sea.  The  total  solids  should 
not  much  exceed  4  or  5  parts  in  100,000,  but  a  larger  amount  is 
sometimes  due  simply  to  the  solvent  action  of  the  water  on  the 
cement  lining  of  the  cistern.  Dr.  Smart  considers  cistern  waters 
containing  from  o.oio  to  0.020  part  of  albuminoid  ammonia  in 
100,000  as  usable,  and  regards  those  containing  over  0.020  part  as 
dangerous,  but  as  much  as  o.oio  ought  to  awaken  suspicion  and 
give  rise  to  inquiry.  The  following  table  contains  the  results  of 
the  examination  of  a  number  of  cistern  waters  in  various  localities. 


TABLE  V. — EXAMINATION  OF  CISTERN  WATERS. 
[Results  expressed   in  Parts  in  100,000.] 


LOCALITY 

TOTAL  SOLIDS 

AMMONIA. 

"  ALBUMINOID 
AMMONIA." 

ORGANIC 
CARBON. 

ORGANIC  NI- 
TROGEN. 

CHLORINE. 

[ 

AUTHORITY. 

Oakham    Eng 

11.70 
8.10 
9.42 

5-28 

12.  OO 
5-28 
6.56 

3-24 
4.80 
3.48 
5.20 

5-05 
6.QO 

3  60 
2.68 
4.72 
4.48 
7.96 

4.10 

0.005 
0.009 
0.032 
O. 
0.130 
0.013 
0.012 
0.005 
O.O24 
O.O2I 
0.007 
0.002 

0.016 
0.005 
0.004 

0275 

0.027 
0.004 

0.020 

0.008 
o  007 

O.OII 

0.016 
0.007 
0.007 
0.015 
0.008 
0.008 
0.123 

0.055 
0.118 

0.016 
0.^60 

0331 
0.167 
0.215 
0.142 
0.154 

0.090 
O.O2I 
0.06  1 
0.029 
0-053 

1.  10 
O.go 
0.80 
0.90 

1.60 

0.32 
0.36 

O.IO 
0.12 
0.69 
0.70 

o  70 

0.52 

0.52 

0.55 

2.76 
1.97 

trace 
trace 

Riv.  Poll.  Com.f 

X                  t«                  « 

«          11          It 

W.  R.  Nichols  $ 

<                < 
<                < 
<               < 
<                < 

C.  W.  Dabneyg 
«                < 
C.   R.   Stuntz|| 

Epsom    Eng  .  .  .  . 

Goring   Eng 

Podehole,  Eng  
Sheffield  Barracks.. 
Boston,  Mass  
Same,   filtered*... 
Another 





Same,   filtered*... 
Another  

Same,  filtered*..  .  . 
Wilmington,  N.  C. 
Another  



.... 

Another  
Cincinnati    O 

Another   

.... 

.... 

Another  
Another 

Another.  . 

The  table  might  be  extended  indefinitely,  but  the  results  have 
little  real  significance  except  in  connection  with  a  minute  knowl- 
edge of  the  history  of  the  various  samples. 

While  rain  water,  on   account  of  its  softness,  is  peculiarly 

*  These  cisterns  were  provided  with  a  brick  filtering-wall. 

f  Sixth  Report,  p.  29. 

j  Filtration  of  Potable  Water,  p.  83. 

§  Report  North  Carolina  Agricultural  Experiment  Station,  1881,  p.  158, 

|  Report  of  Water  Department,  Cincinnati,  1880,  p.  80. 


52  WATER  SUPPLY. 

adapted  to  use  in  washing  and  in  cooking,  it  is  also  wholesome 
as  a  beverage  if  collected  so  as  to  be  reasonably  pure.  There 
has,  however,  long  been  an  opinion  that  snow  water  is  unwhole- 
some. Dr.  Charles  Brewer,  U.  S.  A.,  says  that  "  mountaineers 
(in  the  West),  to  whose  long  observation  and  experience  in  the 
wilds  some  attention  is  due,  attribute  the  origin  of  the  so-called 
mountain  fever  to  the  melting  of  snows  and  the  drinking  of  snow 
water."  Dr.  Smart  *  quotes  facts  to  show  that  this  suspicion  is 
well  grounded,  and  says  that  "  snow  water,  therefore,  pure  as  it 
seems,  must  not  be  accepted  as  innocent  until  its  freedom  from 
organic  ammonia  in  deleterious  or  suspicious  quantity  has  been 
proved."  This  applies  especially  to  snow  melting  and  flowing  in 
the  mountain  streams.  As  collected  with  the  rain  and  stored  in 
cisterns  it  is  wholesome,  as  far  as  we  know.  (Compare  p.  100). 

NATURAL  AND   ARTIFICIAL  ICE. 

As  the  rain  is  water  which  has  been  more  or  less  completely 
purified  by  a  natural  process  of  distillation  and  condensation,  so 
ice  is  water  which  has  been  more  or  less  completely  purified  by 
another  natural  process — that  of  crystallization.  It  is,  therefore, 
not  inappropriate  to  consider  ice  in  this  connection. 

The  great  extent  to  which  ice  is  used  in  many  parts  of  the 
United  States  makes  its  purity  a  matter  of  very  considerable 
importance.  The  surface  water  supplies,  even  of  Northern  cities, 
become  heated  in  summer  so  that,  to  cool  the  water,  at  least 
half  its  own  weight  of  ice  is  needed,  and  very  much  more  than 
this  is  often  used  in  practice. 

When  ice  forms  in  or  on  a  body  of  water,  the  bulk  of  which 
remains  unfrozen,  it  is  generally  supposed  that  foreign  sub- 
stances are  excluded  and  that  the  ice  itself  is  essentially  pure. 
It  is  true  that  foreign,  especially  saline,  substances  are  excluded 
to  a  large  extent,  but  the  ice  always  retains  more  or  less,  and, 
if  the  water  contains  organic  impurities,  the  ice  will  contain  them 
also.  In  fact,  a  pond  or  river  which  is  not  fit  for  a  water  supply 
on  account  of  present  evident  contamination  should  not  be  used 
as  a  source  of  ice  supply.  It  is  also,  unfortunately,  the  case  that 
ice  is  often  cut  in  winter  on  shallow  ponds  which  for  a  consider- 

*  Buck's  Hygiene,  ii,  p.  133. 


DANGERS   OF  IMPURE   ICE.  53 

able  portion  of  the  year  have  no  existence  or  exist  merely  as 
stagnant  pools.  That  such  ice  should  be  wholesome,  ought  not 
to  be  expected,  and  there  are  well  authenticated  cases  on  record 
where  sickness  has  arisen  from  the  use  of  impure  ice.  Such  a  case 
of  well-marked  character  occurred  in  1875  at  Rye  Beach,  N.  H.* 
The  ice  had  been  cut  on  a  brackish  stagnant  pond  into  which  a 
small  brook  brought  a  quantity  of  saw-dust  from  several  saw- 
mills. Here,  the  trouble  was  ascribed  to  the  presence  of  decom- 
posing organic  matter.  That,  in  some  cases,  the  germs  (if  they  be 
germs)  of  specific  diseases  might  retain  their  vitality  even  if 
frozen  into  the  ice,  we  can  but  regard  as  possible  from  what  we 
know  of  the  endurance  of  the  spores  of  the  lower  algae  ;  at  any 
rate,  ice  should  not  be  cut  on  contaminated  waters. 

It  is  unfortunately  true  that  when  public  attention  is  called 
to  a  possible,  but  hitherto  little  noticed  cause  of  disease,  exag- 
gerated statements  are  sure  to  be  disseminated  through  the 
public  prints  and  otherwise — statements  which  have  a  basis  of 
truth,  but  which  are  so  presented  as,  oftentimes,  to  awaken  un- 
necessary anxiety  and  alarm.  The  statement — "  The  old  idea 
that  water  purifies  itself  by  freezing  is  now  pretty  generally 
abandoned  " — is  true,  if  it  means  that  water  does  not  thus  purify 
itself  completely ;  it  is  untrue  as  far  as  it  naturally  leads  to  the 
inference  that  water,  in  freezing,  does  not  purify  itself  at  all. 
Further,  the  author  believes  that  the  following  statements  (in 
which  the  italics  are  his),  even  if  hereafter  proved  true,  are  cer- 
tainly premature,  and  have  not  been  proved  by  experiments 
hitherto  published.  "  The  even  more  dangerous  organic  im- 
purities resulting  from  human  and  other  animal  waste  are  retained 
in  ice  unchanged  as  regards  both  quality  and  quantity,  the  latter 
indeed  being  likely  to  be  increased''  "  The  germs  of  infectious 
disease  .  .  .  are  retained  in  ice  unaffected,  and  from  their 
comparative  lightness  are  so  concentrated  therein  as  to  number  that 
they  exist  in  even  greater  quantity  than  in  the  same  amount  of 
water,  under  similar  circumstances,  at  other  seasons  of  the  year."  f 

Large  quantities  of  artificial  ice  are  now  made  in  the  United 
States,  and  in  a  number  of  Southern  cities  the  artificial  product 

*  See  a  paper  by  A.  H.  Nichols,  M.  D.,  in  the  Seventh  Report  of  the  Mass.  State 
Board  of  Health,  1876,  p.  465. 

f  The  Dangers  of  Impure  Ice  in  The  Sanitarian  for  May,  1882.  See  also  a  paper  on 
Impure  Ice,  in  the  Fifth  Annual  Report  of  the  Connecticut  State  Board  of  Health,  1883. 


54  WATER  SUPPLY. 

has  driven  the  natural  ice  from  the  market.  With  some  of  the 
machines,  distilled  water  alone  is  frozen  ;  with  others,  ordinary 
well  or  other  water.  Ice  machines,  on  a  small  scale,  are  used 
also  in  hotels  for  freezing  carafes,  etc.  Particular  care  should  be 
used  with  reference  to  the  water  employed  in  making  artificial 
ice,  because  the  water  is  frozen  solid,  and  whatever  is  dissolved  or 
suspended  in  the  water  must  remain  in  the  ice.  In  one  machine, 
however  (Beath's  patent),  the  ice  is  formed  by  causing  water  to 
flow  over  pipes  through  which  the  freezing  agent  flows.  Only  a 
part  of  the  water  used  is  actually  frozen  as  it  flows  over  the 
pipes  or  the  continually  increasing  thickness  of  ice,  and  the  bulk 
of  the  impurities,  dissolved  or  suspended,  flows  away. 

Chemical  Examination  of  Ice. 

The  standard  of  purity  for  ice  should  be  placed  very  high. 
Ice  should  contain  very  little  dissolved  matter,  next  to  no  chlo- 
rine, and  the  "albuminoid  ammonia"  should  not  exceed  0.005 
part  in  100,000.  Great  care  must  be  exercised  in  preparing  the 
sample  for  analysis,  because  the  ice  in  melting  attracts  organic 
impurities  from  the  air. 

In  fact,  one  method  which  has  been  proposed  for  examining 
the  air  for  organic  matter,  consists  in  employing  a  glass  funnel 
drawn  to  a  point  and  filled  with  fragments  of  ice.*  The  moisture 
in  the  air  condenses  as  dew  upon  the  outside  of  the  funnel, 
trickles  down  into  the  vessel  below,  and  the 
water  thus  collected  is  examined  for  organic 
matter  in  various  ways.  For  this  reason,  also, 
the  fact  that  the  drip  from  refrigerators  often 
becomes  offensive  when  allowed  to  stand  in  a 
warm  room,  does  not  show  necessarily  that 
the  ice  used  was  impure. 

In  melting  ice  for  analysis,  a  fair  specimen 
cake  should  be  selected  and  broken  into  frag- 
ments in  a  clean  place.  The  fragments  may 
then  be  placed  in  a  wide-mouthed  bottle  cov- 
ered with  a  plate  of  glass,  and,  when  enough 
FIG.  5.  Of  the  jce  has  meited  to  have  washed  itself, 

*  Smee  :  Social  Science  Transactions,  1875,  p.  486.  The  figure  is  from  Fox's 
Sanitary  Examination  of  Water,  etc. 


CHEMICAL  EXAMINATION   OF  ICE. 


55 


this  portion  of  water  should  be  poured  away,  and  the  remainder, 
after  melting,  be  subjected  to  analysis.  Or  the  fragments  may 
be  placed  in  a  large  funnel  covered  with  a  plate  of  glass  until  5 
or  10  per  cent  has  melted,  and  the  remainder  be  then  transferred 
to  the  wide-mouthed  bottle  without  touching  the  ice  with  the 
hands.  Since  even  the  best  of  ice  is  liable  to  have  bits  of  organic 
substances  frozen  into  it  here  and  there,  the  "  albuminoid  am- 
monia" should  be  determined  also  in  the  water  which  has  been 
filtered  through  paper.  It  must  also  be  remembered  that  the 
ice  which  is  sold  for  family  use  often  is  partly  "  snow  ice,"  and 
that  the  snow,  in  falling,  always  brings  down  ammonia  from  the 
atmosphere.  Table  VI  contains  the  results  of  a  number  of 
chemical  examinations  of  ice  from  various  sources. 

TABLE  VI. — EXAMINATION  OF  (MELTED)  ICE. 
[Results  expressed  in  Parts  in  100,003.] 


DESCRIPTION. 

TOTAL  SOLIDS. 

AMMONIA. 

"  ALBUMINOID 
AMMONIA." 

CHLORINE. 

AUTHORITY. 

Rye  Beach,  N.  H.     Supposed  cause  of  sickness. 
Same,  fil  tered  through  paper  

13-52 
9.72 
0.76 
5.00 
S.oo 
2.50 
9.2 
2.4 
0.8 

1.2 
LSI 
0.44 

0.0208 
0.0213 
0.0045 
0.0060 
0.0064 
0.0060 
0.0026 
0.0066 
0.0180 
0.0260 
0.0072 
0.0077 

0.0704 
0.0165 

0.0075 
0.0064 

O.OIIO 

0.0440 
0.0190 
0.0160 
o  0160 
0.0061 
0.0013 

3-2 

trace 

0.4 

°-3 

°-3 

O.O2 

W.  R.  Nichols. 
S.  P.  Sharpies. 
E.  S.  Wood. 

W.  R.  Nichols. 

Boston  Ice  Company,  1875  

Fresh  Pond,  near  Boston,  1878 

Spy  Pond,        "            "          "   
Little  Spy  Pond,  near  Boston,  1878  
Horn  Pond,             "          "        1876*  

Hammond's  Pond,  u          "        1877  

Jamaica  Pond  Ice  Co.,  1877  

Another  sample  of  same                .... 

Pittsfield,  Mass.,  1876  
Same,  filtered  through  paper  .... 

*  The  large  amount  of  impurity  in  this  case  was  probably  due  to  some  local  and 
accidental  cause  :  this  ice  was  thought  to  cause  sickness. 


CHAPTER  IV. 

SURFACE  WATERS  AS   SOURCES  OF  SUPPLY. 

THE  character  of  the  water  which  flows  in  the  streams  and 
is  stored  in  the  lakes  and  ponds  of  any  region  depends  largely 
upon  the  geological  character  of  the  country.  Where  impervious 
rocky  strata  predominate,  the  water  flows  off  from  the  surface 
readily,  and  the  streams  carry  water  free  from  any  very  consider- 
able amount  of  dissolved  substances :  where  the  water  soaks 
quickly  into  the  ground  and  the  streams  and  lakes  are  fed  by 
springs,  or>  at  least,  by  water  which  has  passed  for  some  distance 
underground,  the  amount  of  dissolved  matter  becomes  more  con- 
siderable. As  a  rule,  the  surface  waters  contain  less  dissolved 
matter  and  are  softer  than  the  well  waters  (ground  water)  of  the 
same  region ;  on  the  other  hand,  they  generally  contain  more 
organic  matter  of  animal  and  vegetable  origin,  they  are  often 
colored,  they  are  liable  to  be  turbid  or  to  become  so  at  time  of 
flood,  and  are,  in  several  respects,  more  subject  to  variation  than 
the  ground  water. 

While  much  that  might  be  said  with  reference  to  surface 
waters  will  apply  both  to  running  streams  and  to  ponded  waters, 
it  will  be  convenient  to  divide  the  subject,  discussing  first  the 
matters  of  turbidity  and  pollution,  which  are  peculiarly  felt  in 
the  case  of  rivers,  and  subsequently  discussing  the  difficulties 
arising  from  variable  temperature  and  from  animal  and  vegetable 
growths,  which  are  felt  peculiarly  in  the  case  of  ponded  waters. 

Turbidity  of  Streams. 

It  is  hardly  necessary  to  dwell  upon  the  fact  that  rivers  are 
frequently  objectionable  as  sources  of  supply,  on  account  of  the 
large  amount  of  suspended  matter,  mainly  clay,  which  many 
of  them  carry  invariably  and  others  at  time  of  flood.  Some- 
thing will  be  said  of  this  matter  in  connection  with  sedi- 
mentation in  Chapter  VIII :  at  present,  it  will  suffice  to  call 


THE   POLLUTION   OF   STREAMS. 


57 


attention  to  Table  VII  (made  up  from  statements  in  Geikie's 
Text-book  of  Geology)  which -shows  the  amount  of  suspended 
matter  in  various  rivers,  and  also  shows  that  the  amount  varies 
very  much  in  the  same  stream  under  different  circumstances. 

TABLE  VII. — AMOUNT  OF  SUSPENDED  MATTER  IN  VARIOUS  RIVERS. 


RIVER. 

DATE. 

LOCALITY  AND  CONDITION. 

SUSPF 

MAI 

EXPRE 

PARTS  IN 

by 
weight. 

NDED 
TER 
5SED  IN 
100,000. 

by 
volume. 

PARI 
WATE 

I  PA* 

SEDII 

by 
w'g't. 

17,000 
7,000 
230 

45 

rsOF 
RFOR 
/T  OF 
dENT. 

by 
vol. 

AUTHORITY. 

Rhone  
Rhone  

Rhine 

1844 

Dec      49 

1862      71 

Lycns.          .     .       .   

5-88 

.... 

.... 

'..'.'. 

Aries   low  water 

"      flood   

434.78 

.... 

50.00 

Strasburg,  July  and  Aug  

50,000 
4,878 

16,000 

Daubr^e. 
Horner. 
Bischof. 

Stiefensand. 
Hartsoeker. 
Chandellon. 

Hartley. 
Spittell. 
Lombardini. 
Payen. 

Everest. 
Login. 

Humphreys 
and  Abbot. 

6.25 

Bonn                     

Bonn,  after  dry  weather  
Uerdingen,  after  sudden  floods. 
In  Holland 

1.73 
78.00 

1,000,00 

57,800 
1,282 

2,100 
71,420 
10,000 

3,060 

'"48 

1,000 

428 

510 

1,700 

5,725 

1,500 

100 

s'-a% 

:.-r 

856 

1,021 

2,900 

Maximum          

47.61 

Danube  
Vistula  
Po 

Mean  

IO.OD 

Mean  
Maximum  

32.68 

17.20 
2,083.00 
333-  op 

In  flood  
Mean                  . 

2,083.33 

Durance.... 
Ganges  
Irrawaddy.. 
Mississippi. 

• 

In  flood  

233-95 
196.08 
58.82 

17.47 
66.66 

116.82 
97-94 

'34^48 

Yearly  mean  

In  flood  
Low  water  
Mean 

The  Pollution  of  Streams. 

Owing  to  facilities  for  transportation,  to  available  water- 
power,  and  also  to  the  opportunities  furnished  for  the  discharge 
of  waste  material,  running  streams  naturally  attract  to  their 
banks  manufactories  and  towns,  and,  in  turn,  become  polluted 
by  their  refuse. 

In  a  thickly  settled  manufacturing  country  like  England, 
where,  moreover,  the  streams  are  comparatively  small,  the  pollu- 
tion may  become  very  serious.  In  Great  Britain  the  matter  has 
been  the  subject  of  thorough  investigation  by  two  Royal  Com- 
missions, appointed  respectively  in  1865  and  1868,  "to  inquire 
into  the  best  means  of  preventing  the  pollution  of  rivers." 

The  statement  of  the  Commissioners  with  reference  to  the 
Aire  and  Calder,  although  it  has  been  frequently  quoted,  has  not 
lost  in  emphasis : 


58  WATER  SUPPLY. 

"  The  rivers  Aire  and  Calder  and  their  tributaries  are  abused 
by  passing  into  them  hundreds  of  thousands  of  tons  per  annum 
of  ashes,  slag  and  cinders  from  steam-boilers,  furnaces,  iron- 
works  and  domestic  fires  ;  by  their  being  made  the  receptacle, 
to  a  vast  extent,  of  broken  pottery  and  worn-out  utensils  of 
metal,  refuse  brick  from  brick-yards  and  old  buildings,  earth, 
stone  and  clay  from  quarries  and  excavations,  road-scrapings, 
street-sweepings,  etc. ;  by  spent  dye-woods  and  other  solids  used 
in  the  treatment  of  worsteds  and  woollens  ;  by  hundreds  of  car- 
casses of  animals,  as  dogs,  cats,  pigs,  etc.,  which  are  allowed  to 
float  on  the  surface  of  the  streams  or  putrefy  on  their  banks  ; 
and  by  the  flowing  in,  to  the  amount  of  very  many  millions  of 
gallons  per  day,  of  water  poisoned,  corrupted,  and  clogged  by 
refuse  from  mines,  chemical  works,  dyeing,  scouring  and  fulling 
worsted  and  woollen  stuffs,  skin-cleaning  and  tanning,  slaughter- 
house garbage,  and  the  sewage  of  towns  and  houses." 

"  Bradford  is  an  ancient  town  situated  on  a  '  beck '  about  four 
miles  south  of  the  river  Aire,  into  which  the  water  of  this  beck 
falls.  It  is  the  center  of  the  worsted  district."  The  Commis- 
sioners allude  to  the  increase  of  population  and  to  the  increased 
pollution  from  dye-works,  from  soap-suds,  and  from  refuse  of 
various  kinds  produced  in  manufactures.  "  The  whole  of  the 
sewage  of  Bradford,  and  of  the  populous  district  above  the  town, 
flows  into  the  beck,  producing  an  indescribable  state  of  pollu- 
tion. It  has  become  a  Yorkshire  proverb  of  comparison  for  any 
foul  stream,  to  say  of  it  that  it  is  as  polluted,  as  Bradford  Beck. 
At  the  time  of  our  inquiry  Bradford  Beck  was  the  source  of 
supply  of  the  Bradford  Canal,  the  fluid  of  which  became  so  cor- 
rupt in  summer  that  large  volumes  of  inflammable  gases  were 
given  off,  and,  although  it  has  usually  been  considered  an  impos- 
sible feat  '  to  set  the  River  Thames  on  fire,'  it  was  found  practi- 
cable to  set  the  Bradford  Canal  on  fire,  as  this  at  times  formed 
part  of  the  amusement  of  boys  in  the  neighborhood.  They 
struck  a  match  placed  on  the  end  of  a  stick,  reached  over,  and 
set  the  canal  on  fire,  the  flames  rising  six  feet  high  and  running 
along  the  surface  of  the  water  for  many  yards  like  a  will-o'-the 
wisp ;  canal  boats  have  been  so  enveloped  in  flame  as  to  frighten 
persons  on  board." 

The  river  Irwell,  near  its  source,  "  is  of  excellent  quality  for 
all  domestic  purposes."     It  flows,  however,  through  the  midst  of 


THE   POLLUTION   OF   STREAMS.  59 

a  manufacturing  district,  and  finally  passes  through  Manchester 
before  it  empties  into  the  Mersey.  At  Manchester  the  slug- 
gishly flowing  stream  is  black  as  ink,  and  it  is  there  joined  by  the 
Irk  and  Medlock,  streams  not  less  polluted  than  itself. 

Of  the  Clyde,  the  following  are  bits  of  evidence  : 

"At  one  time  the  Clyde  was  comparatively  pure  and  limpid — 
salmon  fishing  within  the  precincts  of  the  harbor  being  very  pro- 
ductive. Now,  through  Glasgow  downwards,  but  diminishing 
below  the  mouth  of  the  Cart,  it  is  very  foul  and  turbid  ;  in  short 
a  gigantic  open  sewer,  noxious  gases  being  continually  evolved, 
which,  during  summer,  are  so  overpowering  as  to  force  the  bulk 
of  the  passenger  traffic  from  the  river  to  the  rail." 

"  The  harbor  is  more  like  a  gigantic  cesspool  than  a  harbor  in 
the  proper  acceptation  of  the  term." 

"  In  summer  time  there  is  a  perfect  commotion  with  air  and 
gas  bubbles  over  the  whole  surface  of  the  water,  and  it  is  so  bad 
that  we  cannot  use  it  for  the  boilers  of  the  little  steam  ferry- 
boats that  ply  across  the  river." 

While  the  rivers  of  Great  Britain  are  probably  polluted  gen- 
erally to  a  greater  extent  than  those  of  most  other  countries,  the 
trouble  is  by  no  means  peculiar.  In  France  the  condition  of  the 
Seine  below  Paris  has  led  to  the  appointment  of  several  depart- 
mental and  municipal  commissions,  and  to  the  proposal  of  exten- 
sive and  costly  plans  for  disposing  of  the  sewage  of  the  city. 
Other  rivers  of  France,  as,  for  instance,  the  Vesle,  at  Rheims, 
have  become  the  receptacles  of  town  and  manufacturing  refuse 
so  as  to  call  imperatively  for  restrictive  action.  In  Germany  the 
increasing  pollution  of  the  sluggish  Spree  by  the  sewage  of 
Berlin  was  one  of  the  moving  causes  which  has  led  to  an  entire 
change  of  the  system  of  sewerage,  and  to  the  attempt  at  purifi- 
cation and  utilization  of  the  entire  sewage  of  the  city  on  sewage 
farms. 

In  this  country,  many  of  our  streams  carry  such  a  volume  of 
water  that  the  refuse  of-  the  largest  cities  is  soon  lost ;  but  some 
of  the  smaller  rivers,  for  a  portion  of  their  course  at  any  rate, 
are  rendered  unfit  for  domestic  use.  The  Blackstone  River,  in 
Massachusetts,  receives  the  sewage  of  Worcester  and  causes 
complaint  from  the  towns  and  manufactories  on  its  banks.  The 
Schuylkill  and  Passaic  rivers  are  no  longer  fit  for  water  supply 
where  water-works  now  exist.  The  Chicago  River  was  an  ex- 


60  WATER  SUPPLY. 

ceedingly  foul  stream — if  stream  it  could  be  called — until  it  was 
diverted  into  'the  Illinois  River ;  and  other  examples  might  be 
cited.  The  contamination  of  the  water  of  the  Great  Lakes,  in 
the  neighborhood  of  cities  like  Cleveland,  Chicago  and  Milwau- 
kee, is  a  very  serious  matter.  There  is  a  limit  to  the  distance  to 
which  tunnels  can  be  carried  into  the  open  lake,  and  the  problem 
of  disposing  of  the  sewage  of  the  cities,  otherwise  than  by  dis- 
charging it  into  the  lake,  is  one  which  will  soon  compel  solution. 

It  is  not  our  purpose  to  enter  into  details  as  to  the  nature' 
and  amount  of  the  polluting  materials  which  are  discharged  by 
various  manufacturing  industries,  nor  to  discuss  how  far  the  indi- 
vidual substances  are  injurious  to  plants  or  to  fish,  or  how  far 
they  render  the  water  unfit  for  drinking  and  for  other  domestic 
purposes.*  We  may  admit  that  certain  substances  are  injurious, 
even  in  small  amount;  but,  while  this  is  true,  it  is  also  true 
that  much  manufacturing  refuse  is  of  such  a  character  as  to 
be,  except  in  excessive  quantities,  of  no  appreciable  influence  on 
the  human  system.  Thus,  the  addition  to  a  water  of  most  of 
the  ordinary  salts  of  lime,  soda,  potash,  etc.,  would  not  produce 
any  deleterious  effect,  although  the  addition  of  lime  compounds 
would  increase  the  hardness  and  render  the  water  less  desirable 
for  washing.  Again,  in  the  case  of  many  waste  liquors  of  offen- 
sive appearance,  the  actual  amount  of  matter  which  is  really 
injurious  or  of  suspicious  character  is  comparatively  small.  Thus, 
in  the  case  of  some  of  the  organic  dyestuffs,  the  weak,  spent 
dye-liquors,  although  they  communicate  a  very  foul  appearance 
to  the  water  for  some  distance,  yet  contain  a  comparatively  small 
amount  of  solid  matter,  and,  if  discharged  into  a  stream  of  con- 
siderable size,  are  soon  disseminated  through  it,  and  diluted  to  a 
very  great  extent. 

Very  different,  however,  in  character  and  importance,  from 
much  of  the  refuse  of  manufacturing  establishments,  is,  as  we 
have  seen,  the  sewage  proper — that  is,  the  excremental  matters 
from  factories  and  towns — and  the  refuse  from  particular  opera- 
tions, such  as  tanning,  slaughtering,  rendering,  wool-pulling,  etc. 

*  These  matters  are  very  fully  discussed  in  the  reports  of  the  Rivers  Pollution 
Commissions  of  Great  Britain.  A  brief  statement  with  reference  to  the  chemicals  and 
other  materials  used  in  various^  manufacturing  operations  and  with  reference  to  the 
liquid  refuse  discharged  from  them,  is  given  in  the  Report  of  the  Mass.  State  Board 
of  Health,  1876  :  Special  Report  on  the  Pollution  of  Rivers  by  J.  P.  Kirkwood,  C.E. 


THE  POLLUTION  OF  STREAMS. 


6l 


1 


With  our  present  information,  too  much  stress  cannot  be  laid 
upon  the  importance  of  preventing  the  discharge  of  such  refuse, 
and  of  sewage  in  its  more  restricted  sense,  into  any  stream  of 
pond  used,  or  likely  to  be  used,  as  a  source  of  water  supply. 

The  importance  of  this  matter  is  underrated  for  two  reasons: 
first,  because  of  a  belief  that  an  impure  and  polluted  water  rap- 
idly purifies  itself  by  natural  means ;  and,  second,  because  of  the 
feeling  that  a  water  to  be  prejudicial  to  health  must  be  polluted 
to  such  an  extent  that  the  animal  matter  may  be  recognized  by 
chemical  tests. 

That  a  polluted  water  in  its  flow  does  become  purer,  no  one 
can  doubt  who  has  followed  the  course  of  a  polluted  stream ; 
chemical  analysis  proves  the  same  thing.  There  is,  however, 
much  difference  of  opinion  as  to  the  method  by  which  the  puri- 
fication takes  place,  and  also  as  to  the  extent  to  which  we  may 
suppose  that  the  disease-producing  something  is  eliminated. 

TABLE  VIII. — THE  SEINE  ABOVE  AND  BELOW  PARIS.* 


KILOMETERS. 

LOCALITY. 

ORGANIC 

NITROGEN. 

Grams  per 
cubic  meter. 

TOTAL 
COMBINED 
NITROGEN. 
Grams  per 
cubic  meter. 

DISSOLVED 
OXYGEN. 
Cubic 
centimeters 
per  liter. 

Corbeil  (above  Paris)  

Q.^2 

0 

8 

qi 

Pont  de  la  Tournelle,  Paris  
Auteuil  (below  the  city  but   above 
the  outlets  of  the  main  sewers)  .  .  . 
Pont  d'Asnieres  (above  main  sewer) 
Epinay  (below  all  sewers) 

0.85 
I  26 

1.9 
q  o 

8.05. 

5-99 
5-34 

I  OZ 

78 

Pont  de  Poissy     

O  4^ 

2  2 

6  12 

rn 

Pont  de  Meulan  

O  4O 

8   17 

IOQ 

1.4 

8.06 

150 

10.40 

242 

Rouen 

IO.42 

Table  VIII  contains  the  results  of  partial  examinations  of 
the  Seine  above  and  below  Paris.  At  Epinay,  below  all  the 
sewers,  the  river  is  at  its  worst  as  regards  the  amount  of  nitrogen 
in  the  form  of  ammoniacal  salts  and  organic  compounds,  and  the 
dissolved  oxygen  is  reduced  to  a  minimum.  After  flowing  some 
75  or  100  kilometers,  the  river  regains  its  purity  as  far  as  appear- 
ance and  chemical  tests  can  indicate. 

*  Assainissement  de  la  Seine,  etc.,  deuxieme  partie,  II  Annexes,  p.  8  ;  also  Rap- 
port de  MM.  Schloesing  et  A.  Durand-Claye.  Congres  international  d'hygiene, 
Paris,  1878,  p.  314. 


62 


WATER   SUPPLY. 


TABLE  IX. — SELF-PURIFICATION  OF  STREAMS. 

[Results  expressed  in  Parts  in  100,000.] 


MILES. 

LOCALITY. 

TOTAL 
SOLIDS. 

AMMONIA. 

"  ALBUMINOID 
AMMONIA." 

CHLO- 
RINE. 

Blacks  tone  River,  1875. 
North  Pond,  above  pollution  

4.  2O 

0.0107 

O.O2I3 

o  18 

City  Reservoir   gate-house  .  . 

1   76 

O  0072 

O  O21^ 

O   12 

Mill  Brook   below  sewers  

2-J    44 

O  9600 

o  1  109 

T    80 

Blackstone  River,  at  sash  factory  

8  04! 

O.OQQ2 

O   O'UD? 

O   Q2 

Blackstone  River   at  Blackstone 

4  80 

O   OOOQ 

o  0139 

u   "^ 

o  30 

•*D 

0 
"a 
13* 

O 

«i 

Merrimack  River,  1873. 

Mean  of  1  1  examinations  above  Lowell.  .  . 
Mean  of  12  examinations  above  Lawrence. 
Mean  of  n  examinations  below  Lawrence 

Merrimack  River,  1879.* 

Mean  of  2  examinations  above  Lowell.  .  .  . 
Mean  of  4  examinations  above  Lawrence  . 

4.10 
4.10 

4-43 

5-50 
7.56 

O.OO47 
0.0044 
0.0031 

O.002I 

O.OOlS 

O.OII4 
O.OIIO 

0.0127 

0.0132 
0.0131 

0.14 
O.2O 

0.18 

0.40 
0.44 

Table  IX  contains  results  which  are  less  striking  but  which 
point  in  the  same  direction.  The  Blackstone  Valley  is  the  seat 
of  considerable  manufacturing  industries,  there  being  on  the 
stream  and  its  tributaries  44  woolen  mills,  27  cotton  mills,  12  iron 
works,  I  tannery  and  I  slaughter  house.  Some  of  the  mills 
cause  local  pollution,  but  the  chief  source  of  contamination  is 
the  sewage  of  the  City  of  Worcester— some  2,000,000  gallons  in 
24  hours — which  flows  into  Mill  Brook  and  thence  into  the 
river. 

"  The  water  of  Mill  Brook,  after  it  has  received  the  sewage  of 
Worcester,  is  shown  to  be  very  impure  in  this  table,  and  on  the 
Blackstone  River,  at  the  sash  factory,  about  five  miles  lower 
down,  it  still  gives  unmistakable  signs  of  the  influence  of  this 
pollution  ;  but  at  Blackstone,  twenty-five  miles  below  Mill  Brook, 
the  dilution  produced  by  numerous  small  streams  delivering  into 
the  main  river  between  these  points  has  all  but  obliterated  the 
evidence  of  impurity,  so  far  as  analysis  can  expose  it,  the  only 
marked  difference  here  in  the  table  between  the  water  at  Black- 
stone  and  the  head  water  of  the  river,  being  in  the  amount  of 
chlorine,  the  increase,  however,  of  this  evidence  of  impurity  not 
being  so  great  as  to  condemn  the  water  (by  this  test)  for 
domestic  or  any  other  use.  It  is  to  be  noted,  however,  that  the 
river  at  this  time  was  not  at  its  very  low  dry-weather  stage, 


*  E.  S.  Wood,  M.D. 


THE  POLLUTION  OF  STREAMS.  63 

which  usually  occurs  in  October  or  November,  when  it  occurs  at 
all.  In  extreme  low  water,  the'  river  would  give  greater  tokens 
of  impurity."  * 

Of  the  Merrimack  River  it  may  be  said  that,  in  1873,  when 
some  of  the  examinations  were  made,  Lowell  had  a  population 
of  about  41,000  and  Lawrence  of  about  30,000;  further,  at 
Lowell  there  are  some  75  mill  buildings,  in  which  about  16,000 
operatives  are  employed.  About  10,000  horse  power  is  derived 
from  the  river,  and,  in  addition,  steam  power  is  used  to  the  extent 
of  6,000  horse  power.  The  Merrimack  Manufacturing  Company 
alone  consumes,  among  other  things,  7,500  gallons  of  oil  per 
annum,  225,000  pounds  of  starch,  1,100  barrels  of  flour,  2,500,000 
pounds  of  madder,  50,000  of  copperas,  170,000  of  alum,  200,000 
of  sumac,  1,120,000  of  sulphuric  acid,  300,000  of  bark,  350,000  of 
soda-ash,  and  40,000  of  soap.f 

At  Lawrence  there  are  some  25  mills  (buildings),  employing 
9,000  operatives.  The  manufacturing  industry  is  less  at  Law- 
rence than  at  Lowell,  but  it  is  still  very  considerable.  The 
Pacific  Mills,  which  is  the  largest  corporation,  use  some  800,000 
pounds  of  starch,  540  barrels  of  flour,  8,300  gallons  of  oil,  etc.  ^ 

The  questions  naturally  arise,  to  what  causes  are  we  to  ascribe 
the  disappearance  of  the  large  amount  of  polluting  material  in  the 
Seine,  and  in  the  Blackstone,  and  why,  in  the  case  of  the  Merri- 
mack River,  are  we  not  able  to  trace  a  greater  effect  as  produced 
by  the  large  manufacturing  cities  of  Lowell  and  Lawrence. 

In  studying  the  self-purifying  power  of  streams,  let  us  first 
take  an  instance  of  a  substance  whose  course  we  can  trace  more 
easily  than  that  of  animal  refuse,  with  which  we  are,  of  course, 
more  concerned.  The  following  account  from  the  First  Annual 
Report  of  the  Mass.  State  Board  of  Health,  Lunacy  and  Charity 
(1880),  will  furnish  the  illustration  : 

"  On  the  night  of  June  2,  1879,  a  ^re  occurred  in  a  chemical 
works  situated  on  a  brook  whose  waters  eventually  find  their  way 
into  Mystic  Pond,  from  which  a  portion  of  the  city  of  Boston, 
Mass.,  obtains  its  supply  of  water.  As  a  result  of  the  destruc- 

*  Seventh  Annual  Report  of  Mass.  State  Board  of  Health,   1876,  p.  84. 

f  These  figures  are  taken  from  the  "  Statistics  of  Lowell  Manufactures,  January, 
1873,"  published  by  Stone  &  Huse,  Lowell. 

\  "  Statistics  of  Lawrence  Manufactures,  January,  1872."  Published  by  Geo.  S. 
Merrill  &  Co.,  Lawrence. 


64 


WATER  SUPPLY. 


tion  by  fire  of  the  sulphuric  acid  chambers,  a  considerable  quan- 
tity of  sulphuric  acid,  estimated  at  fifty  tons  of  oil  of  vitriol, 
together  with  salt  cake  and  other  chemicals,  was  washed  directly 
into  the  brook,  or  flowed  upon  the  adjoining  meadow-land,  from 
which  it  would  slowly  find  its  way  to  the  stream.  Large  num- 
bers of  fish,  driven  before  the  acid  water,  or  actually  killed  by  it, 
passed  into  the  mill-ponds  below  and  through  the  wheels  of  the 
mills.  Anxiety  was  felt  lest  the  acid  should  reach  Mystic  Pond 
itself ;  and,  five  days  after  the  fire,  specimens  of  the  water  were 
collected  for  analysis.  As  far  as  Mystic  Pond  itself  was  con- 
cerned, the  fears  proved  groundless ;  but  in  the  brook  and  in  some 
of  the  upper  ponds  there  was  an  abnormal  amount  of  dissolved 
matter  and  especially  of  sulphates.  The  most  interesting  point, 
however,  was  with  reference  to  the  acidity  of  the  water.  As  a 
rule,  our  surface  waters  in  Massachusetts  are  naturally  slightly 
alkaline,  and,  when  the  water  is  evaporated  to  dryness,  the  residue 
effervesces,  at  least  slightly,  when  treated  with  acid.*  It  was 
found  that  even  five  days  after  the  fire  the  water  of  the  brook 
itself  and  of  the  nearest  ponds  was  distinctly  acid.  The  amount 
of  acid  was  estimated  by  means  of  a  dilute  solution  of  baryta, 
using  rosolic  acid  as  an  indicator. 

"  The  acidity  was  found  to  be  as  follows,  the  results  being 
expressed  by  stating  how  many  parts  by  weight  of  sulphuric  acid 


ACIDITY. 

if 

ll 

No. 

DATE. 

LOCALITY. 

<  1  ' 

Jg 

w  M  rt 

to 

Co 

oTr 

1* 

1879. 

I 
IV 

June  7,  A.M. 
June  7,  A.M. 

From  brook  just  below  works  ...     
Lower  end  of  Richardson's  Pond,  about  1%  miles  below 

1.74 

S7i5oo 

works  

0.74 

135,000 

V 
II 

June  7,  A.M. 
June  7,  P.M. 

Frye  &  Thompson's  Pond,  about  3  miles  below  works.  .  . 
From  brook  midway  between  Chemical  Works  and  Rich 

0.37 

270,000 

ardson's  Pond,  about  %  mile  below  works  . 

0.18 

555,500 

VI 

June  7,  P.M 

From  canal  at  Montvale,  about  3^  miles  below  works  

0.37 

270,000 

III 

June  8,  P.M 

Upper  end  of  Richardson's  Pond,  X  m^e  below  11  ....... 

0.15 

666,600 

(H2SO4),  or  its  equivalent,  were  present  in  100,000  parts  by  weight 
of  the  water ;  and  also  by  stating,  in  round  numbers,  with  how 

*  Whether  the  alkalinity  is  to  be  regarded  as  due  in  part  to  the  presence  of  alka- 
line carbonates,  or  as  solely  due  to  the  presence  of  dissolved  carbonate  of  calcium,  is 
uncertain,  as  there  are  no  analyses  which  are  sufficiently  particular  to  determine. 


SELF-PURIFICATION   OF   STREAMS. 


many  parts  of  water  by  weight  one  part  of  sulphuric  acid  was 
diluted. 

"  From  the  point  numbered  VI,  that  is  from  the  canal  at 
Montvale,  samples  were  taken  at  intervals  until  the  water  re- 
turned to  its  alkaline  reaction.  The  results  of  the  examination 
were  as  follows  : 


1  ' 

1 

if. 

^^ 

'3 

•c  s^ 

DATE. 

LOCALITY. 

:g8 

cO 

III 

REMARKS. 

i 

few 

W3  rt  O 

•—  <  U 

e* 

•y'o 

111 

4-7 

1879. 
June    6 

June    7 

Canal  at  Montvale 
Avenue,Montvale 

j.ii.6 
13-9 

O.22 

0-37 

June    9 
June  10 

12.8 

ii.  6 

0.26 
0.22 

.... 

1    The  residue  of  evaporation  did  not 
[       effervesce  with  acid. 

June  13 

9.4 

0.16 

June  15 

10.  1 

j  Slightly 
1  alkaline. 

[I 

J 

June  19 

9.4 

0.16 

1.2 

Residue  did  not  effervesce. 

June  30 
July  8 

7-7 
8.4 

(  Slightly 
1  alkaline. 
i  Slightly 
1  alkaline. 

>•  Residue  did  effervesce  with  acid. 

"  While  the  water  was  acid,  the  residue  of  evaporation  did 
not  effervesce  with  acid,  showing  that  a  part,  at  any  rate,  of  the 
sulphuric  acid  was  neutralized  by  the  carbonates  in  the  water. 
It  may  also  be  noted,  that  some  fragments  of  marble  were  put 
into  some  of  the  water  No.  IV,  which  had  an  acidity  of  0.74; 
after  standing  for  fifteen  hours  the  acidity  had  decreased  to 
o.i  i,  and  after  standing  for  two  and  a  half  days  the  reaction  was 
neutral  or  faintly  alkaline." 

Mystic  Pond  is  about  eight  miles  below  the  works :  samples 
were  taken  from  the  upper  end  of  the  pond  for  several  days,  but 
no  acid  reaction  was  at  any  time  perceptible. 

Thus,  in  the  disappearance  of  the  sulphuric  acid,  we  have 
two  actions  concerned  :  first,  the  chemical  action  by  which  it 
was  converted  probably  into  sulphate  of  lime,  and  then  the 
action  of  dilution,  by  which  all  traces  of  it  were  apparently  lost. 
With  many  inorganic  substances  we  may  predict  what  will  hap- 
pen when  they  come  into  a  stream,  and  the  same  thing  is  true 
5 


66  WATER   SUPPLY. 

of  certain  particular  organic  substances  whose  changes  have 
been  studied  under  various  conditions ;  but  of  the  heterogeneous 
mixture  which  we  speak  of  collectively  as  "  sewage,"  it  would  be 
difficult  to  declare  a  priori  what  changes  would  take  place  and 
what  products  would  be  formed.  There  are,  however,  three 
principal  ways  in  which  a  natural  water  frees  itself  from  organic 
pollution:  (i)  by  oxidation  and  other  chemical  changes;  (2)  by 
deposition  ;  (3)  by  dilution. 

Oxidation. — The  disappearance  of  organic  refuse  is,  no  doubt, 
to  a  certain  extent,  due  to  chemical  changes,  by  which  the  or- 
ganic matter  is  oxidized  and  converted  into  simpler  compounds; 
under  favorable  circumstances  the  destruction  may  be  complete, 
the  nitrogen  appearing  in  ammoniacal  compounds  and  nitrates, 
or  escaping  in  the  free  state,  and  the  carbon  appearing  as  car- 
bonic acid.  That  chemical  action  takes  place  is  made  evident 
enough,  when  the  pollution  is  considerable,  by  the  escape  of  sul- 
phuretted hydrogen,  marsh  gas,  and  other  gaseous  products  of  de- 
composition, as  in  the  case  of  the  Bradford  Beck — alluded  to  on 
page  58.  Of  the  Seine,  it  was  said  in  1874  that,  for  the  greater 
part  of  the  year,  especially  in  warm  weather,  bubbles  of  gas — 
sometimes  a  meter  or  a  meter  and  a  half  in  diameter — were 
continually  rising  to  the  surface  of  the  water,  and  the  passage  of 
a  boat  caused  a  great  ebullition,  and  left  a  mass  of  foam  persist- 
ing for  some  minutes.  The  chemical  change  is  also  marke.d  by 
the  partial  or  total  disappearance  of  dissolved  oxygen,  as  in- 
stanced in  Table  VIII. 

Attempts  have  been  made  to  reach,  by  laboratory  experi- 
ments, some  idea  of  the  amount  of  oxidation  which  may  take 
place  in  a  running  stream  polluted  by  sewage.  The  Rivers 
Pollution  Commission  mixed  urine  with  water  in  the  proper- 
tion  of  one  gallon  of  urine  to  3,077  gallons  of  water.  The 
mixture  was  agitated  from  time  to  time,  and  samples  taken  for 
analysis.  The  results  (expressed  in  parts  in  100,000)  were  as 
follows : 

Organic  Organic 

Carbon.          Nitrogen. 

Immediately  after  mixture,  Feb.  17,  1874  0.282  0.243 

18,  0.298  0.251 

19,  0.244  0.255 

24,  0.225  0.253 

25,  0.214  0.259 
28,                      0.214            0.276 


SELF-PURIFICATION   OF   STREAMS.  67 

In  other  experiments,  a  stream  of  impure  water  was  allowed 
to  flow  from  one  vessel  to  another,  freely  exposed  to  the  air. 
As  a  general  result,  the  commissioners  concluded  that  the  puri- 
fication due  to  actual  oxidation  had  been  much  overrated,  and 
that  there  was  no  river  in  the  United  Kingdom  long  enough,  if 
once  seriously  polluted,  to  purify  itself  in  this  way. 

Certain  chemical  changes,  other  than  those  already  alluded 
to,  will  be  mentioned  in  the  next  paragraph :  we  may  here 
allude  to  the  fact  that  in  the  destruction  of  organic  matter  a 
certain  part  is,  no  doubt,  played  by  the  fish  and  other  animal 
inhabitants  of  the  water,  and  many  of  the  changes  which  seem 
to  be  purely  chemical  appear  to  be  brought  about  wholly  or  in 
part  by  some  of  the  lower  algae  or  by  those  minute  organisms 
which  are  frequently  spoken  of  together  as  "  bacteria."  Thus 
we  know  there  are  certain  algse  which  reduce  the  sulphates  to 
sulphides,  and  the  formation  of  nitrates  in  the  soil  and  in  water 
is  ascribed  also  to  micro-organisms. 

Deposition. — Much  waste  material  thrown  into  rivers  is  made 
up  wholly  or  in  part  of  substances  insoluble  in  water.  A  portion, 
and  a  very  considerable  portion,  even  in  a  running  stream,  is 
deposited  upon  the  bottom  or  stranded  upon  the  banks.  This 
deposition  can  often  be  very  plainly  observed  in  the  immediate 
neighborhood  of  the  points  of  discharge.  It  is  not,  however, 
suspended  matters  only  that  are  removed  by  deposition.  In  the 
first  place,  many  substances  which  seem  to  be  perfectly  dissolved 
are  dragged  out  of  solution  and  carried  down  by  almost  any 
finely  divided  substance.  This  is  especially  true  of  organic 
coloring  matters  and  of  the  nitrogenous  matter  which  gives  rise 
to  the  "  albuminoid  ammonia  "  revealed  by  analysis ;  it  is  true, 
but  to  a  very  limited  degree,  of  some  mineral  salts.  In  the 
second  place,  chemical  changes  take  place  in  the  stream,  espe- 
cially when  refuse  liquids  from  different  sources  meet  and  mix, 
which  result  in  the  formation  of  new  and  insoluble  substances, 
and  these  when  formed  settle  out,  dragging  other  substances 
with  them  as  just  indicated.  The  improvement  in  the  con- 
dition of  polluted  streams  which  appeals  to  the  eye  is  largely 
due  to  deposition. 

The  deposits,  once  formed,  continue  to  undergo  chemical 
change;  they  shift  their  position  with  changing  currents,  and  in 
time  of  flood  may  be  washed  up  and,  mingling  with  earthy 


68  WATER  SUPPLY. 

material  held  in  suspension,  be  swept  on  to  the  sea  or  deposited 
in  some  new  position,  either  lower  down  on  the  stream  or  on 
the  surface  of  overflowed  territory.  Often,  however,  the  character 
of  the  bed  of  the  stream  becomes  permanently  altered  unless 
means  are  taken  by  dredging  or  otherwise  to  remove  the  ac- 
cumulations as  they  increase. 

Dihition. — Probably  the  most  important  reason  of  the  appar- 
ent disappearance  of  sewage  and  other  waste  material,  is  the  fact 
that  the  amount  of  solid  matter  is  so  small  compared  with  the 
volume  of  water  into  which  it  is  thrown,  that  it  is  disseminated 
through  the  mass,  and  thus  lost  to  observation,  and,  in  many 
cases,  to  chemical  tests. 

A  river  in  its  flow  loses  water  by  evaporation,  by  being  di- 
verted for  manufacturing  and  other  purposes,  and  in  some  places, 
through  crevices  in  a  rocky  bed  or  by  a  slower  process  of  per- 
colation if  the  bed  be  gravelly.  On  the  other  hand,  the  stream 
receives  water  from  tributaries  more  or  less  pure  than  itself, 
and  its  volume  is  further  increased  by  the  entrance  of  ground 
water  or  by  actual  springs  rising  in  its  bed.  On  this  account  we 
cannot  calculate  the  extent  to  which  dilution  will  take  place  with 
any  great  accuracy,  but  that  the  apparent  disappearance  of  much 
of  the  foreign  matter  which  finds  its  way  into  the  stream  is 
really  owing  to  dilution  is  evident  when  we  undertake  to  trace 
the  course  of  some  substance  not  liable  to  undergo  any  changes 
which  will  result  in  its  actual  disappearance.  The  chlorine, 
which  exists  in  the  form  of  chloride  of  sodium  (common  salt) 
and  other  chlorides,  furnishes  us  with  what  we  need. 

All  natural  waters  contain  a  small  proportion  of  chlorine,  very 
small  in  inland  waters,  slightly  increased  in  waters  near  the  sea. 
Chlorine  is  a  universal  accompaniment  of  sewage,  generally  in 
the  form  of  chloride  of  sodium  (common  salt),  and  occurs  also  in 
most  manufacturing  refuse.  All  the  chlorine  used  in  the  process 
of  bleaching  is  eventually  washed  away,  and  that  contained  in 
the  various  compounds  of  this  element  which  are  used  in  dye- 
houses  and  print-works  finds  its  way  in  the  end  into  the  drains 
of  the  establishments.  On  this  account,  although  harmless  in 
the  combinations  in  which  it  finally  exists,  its  presence  indicates 
the  presence,  now  or  formerly,  of  refuse  material.  Of  course,  in 
regions  containing  salt-springs  and  salt-deposits,  these  statements 
would  require  modification.  It  is  to  be  remarked  further,  that 


SELF-PURIFICATION  OF  STREAMS.  69 

while  there  do  exist  compounds  of  chlorine  which  are  insoluble 
in  water,  and  other  compounds  which  are  gaseous,  and  while  it  is 
true  that  chlorides  are  absorbed  to  a  limited  extent  by  earth 
filters  and  by  growing  plants,  for  all  practical  purposes  we 
may  say  that  the  chlorides  once  dissolved  in  the  water  are  not 
removed  either  as  insoluble  or  gaseous  compounds. 

If,  now,  we  take  the  case  of  the  Blackstone  River  as  instanced 
in  Table  IX,  page  62,  we  shall  see  that  the  3.80  parts  of  chlorine 
in  Mill  Brook  have  become  0.92  part  five  miles  below,  after  the 
brook  has  been  merged  in  the  river,  and  twenty  miles  further 
still  the  river  water  contains  only  0.36  part.  Believing,  as  we  do, 
that  this  decrease  of  the  chlorine  is  due  almost  entirely  to  dilu- 
tion, we  must  believe  also  that  the  decrease  in  the  amount  of  the 
organic  matter  is  largely  due  to  the  same  cause.  Owing  to  the 
fact  that  the  organic  matter  is  much  more  liable  to  conversion 
into  insoluble  and  volatile  compounds,  no  one  would  deny  that 
an  appreciable  amount  of  organic  matter  is  chemically  changed 
and  actually  destroyed,  but  emphasis  should  be  laid  upon  what 
we  believe  to  be  a  fact — namely,  that  the  apparent  self -purifica- 
tion of  running  streams  is  largely  due  to  dilution,  and  the  fact  that 
a  river  seems  to  have  purified  itself  at  a  certain  distance  below  a 
point  where  it  was  certainly  polluted,  is  no  guaranty  that  the 
water  is  fit  for  domestic  use. 

Referring  again  to  Table  IX,  it  would  appear  that  no  effect 
is  produced  upon  the  waters  of  the  Merrimack  by  the  cities  of 
Lowell  and  Lawrence,  which  throw  into  the  stream  the  greater  part 
of  their  sewage  and  the  waste  from  all  the  mills.  Is  the  organic 
matter  of  all  this  refuse  destroyed  by  oxidation  or  other  chem- 
ical change  ?  Certainly  not !  Let  us  take  simply  the  results  of 
examination  above  and  below  Lawrence.  Between  these  two 
points  the  river  receives  the  refuse  from  nearly  all  the  manufac- 
turing establishments,  a  large  proportion  of  the  excreta  of  the 
factory  operatives,  and  a  portion  of  the  sewage  of  Lawrence. 
Moreover,  the  lower  station  is  so  short  a  distance  below  the  city, 
that  no  chemist,  probably,  would  believe  that  any  considerable 
destruction  of  organic  matter  could  take  place  in  the  rapid  flow 
for  so  short  a  distance,  and  if,  upon  chemical  grounds,  the  evi- 
dence was  not  sufficient,  the  floating  soap-suds,  with  still  unbroken 
bubbles,  and  other  materials  borne  down  upon  the  current  show 
the  same  thing.  Now,  in  spite  of  this  addition,  which  must  be 


70  WATER  SUPPLY. 

considerable,  there  is  only  a  slight  increase  in  the  total  dissolved 
solids,  and  in  the  albuminoid  matters,  while  the  chlorine  is  prac- 
tically the  same  or  slightly  decreased.  We  know,  positively,  that 
chlorine  compounds,  in  large  quantity,  are  thrown  into  the 
river  at  Lawrence,  and  yet,  just  below  the  city,  the  proportion  is 
not  increased.  Although  absolutely  large,  the  amount  is  too 
small  compared  with  the  great  volume  of  water  to  produce  an 
appreciable  increase.  From  these  considerations  with  reference 
to  the  chlorine,  it  is  evident  that,  in  the  case  of  the  soluble 
organic  matter  it  is  not  necessary  to  suppose  any  destruction  or 
decomposition ;  the  apparent  decrease  or  lack  of  increase  may  be 
explained,  as  in  the  case  of  chlorine,  by  the  fact  of  dilution,  and 
where  the  distance  between  the  two  points  of  examination  is  so 
short  as  in  the  instance  now  under  discussion  (above  and  below 
Lawrence),  this  is  no  doubt  the  main  cause  concerned. 

It  may  be  well,  in  this  connection,  to  say  that  it  is  often  diffi- 
cult to  prove  satisfactorily  the  actual  pollution  of  a  stream  until 
by  the  accidental  or  unusual  discharge  of  some  peculiarly  offen- 
sive or  characteristic  substance  the  matter  is  placed  beyond 
doubt.  Carbolic  acid  has  sometimes  served  this  purpose  ;  thus, 
a  few  years  ago,  the  taste  and  odor  of  carbolic  acid  were  so  strong 
in  the  water  supplied  to  Newark,  Jersey  City  and  Hoboken, 
that  the  water  could  not  be  used  for  domestic  purposes.  These 
cities  take  their  water  from  the  Passaic  River  at  a  point  where 
the  stream  is  always  polluted,  but  at  this  time  particular  atten- 
tion was  called  to  the  polluted  condition  of  the  water  supply 
by  the  washing  of  a  quantity  of  carbolized  paper  at  a  mill  on 
one  of  the  tributaries  of  the  stream.*  The  following  circum- 
stance is  related  with  reference  to  the  water  supply  of  Cincin- 
nati, Ohio.f 

"  The  eddy  of  the  Deer  Creek  Canal  caused  much  pollution, 
which  was  brought  to  the  attention  of  the  consumers  in  a 
marked  manner  in  1867  by  the  burning  of  a  large  distillery  on 
the  canal.  The  whiskey  found  its  way  into  the  canal,  thence 
into  the  river,  and  thence  to  the  consumers." 

Much  depends,  of  course,  upon  the  size  of  the  stream  into 
which  the  refuse  is  thrown.  Thus,  while  into  the  Merrimack  at 


*  Leeds  :    Journ.  Amer.  Chem.  Soc. ,  Hi. 
f  Engineering  News,  1881,  p.  162. 


PREVENTION  OF  POLLUTION.  7 1 

Lowell,  even  during  the  summer,  it  would  be  necessary  to  throw 
more  than  one  hundred  tons  of  solid  matter  daily  in  order  to 
increase  the  amount  in  the  water  by  one  grain  to  the  gallon,* 
another  and  smaller  stream  might  be  hopelessly  fouled  by  a 
single  factory. 

Ullik  has  made  some  interesting  calculations  with  reference  to 
the  Elbe,  in  Bohemia,  and  shows  that  the  entire  product  of  the 
well-known  sulphuric  acid  works  at  Aussig,  if  allowed  to  flow 
into  the  river,  would  increase  the  amount  of  sulphates  by  only 
one  twenty-fourth,  and  that  the  mineral  matter  in  the  sewage 
from  all  of  the  5,000,000  inhabitants  of  Bohemia -would  increase 
the  mineral  matter  in  the  stream  by  only  one  twentieth.f 

A  question  which  we  should  be  glad  to  have  answered  is  this : 
To  what  extent  must  a  polluted  liquid  be  diluted  in  order  to  be 
safely  used  for  domestic  purposes  ?  The  answer,  however,  none 
can  give.  We  do  know  this :  it  has  been  shown  by  actual  exper- 
iment that  the  spores  of  some  of  the  lower  orders  of  vegetable 
organisms  are  very  difficult  to  deprive  of  vitality ;  they  may  be 
frozen  or  heated  to  the  boiling  temperature,  or  they  may  be  kept 
in  a  dry  condition  for  years,  and  then,  if  placed  in  a  favorable 
medium,  become  active  and  produce  their  kind.  Admitting  the 
presence  of  disease  germs  in  a  liquid,  the  liquid  may  be  diluted 
until  the  chance  of  taking  even  a  single  germ  into  the  system  is 
so  small  that  it  may  be  disregarded  ;  and  yet,  if  the  prevailing 
theory  be  true,  a  single  germ,  if  taken,  might  produce  disastrous 
results.  It  is  easy  to  push  the  demands  for  purity  to  an  absurd 
extent ;  all  reasonable  precautions  should  be  taken  to  insure 
purity,  but  there  is  a  point  beyond  which  it  is  foolish  to  attempt 
to  go.  In  the  present  state  of  our  knowledge  we  should,  how- 
ever, err  on  the  side  of  safety,  and  the  mere  fact  that  chemical 
analysis  fails  to  detect  impurity  should  not  be  accepted  as  a 
guaranty  that  a  water  is  fit  to  drink. 

Prevention  of  Pollution. 

The  pollution  of  streams  can  be  prevented  only  by  legal 
enactments.  Cities  and  towns  claim  the  right  to  discharge  their 


*  Fifth  Annual  Report  of  the  Mass.  State  Board  of  Health. 
f  Abh.  d.  math,  wissenschf.  Classe  d.  k.  bohm.  Ges.,  x. 


72  WATER  SUPPLY. 

sewage  into  a  water-course  on  which  they  may  be  situated,  and 
unless  a  nuisance  is  thereby  created  within  their  own  boundaries, 
they  are  not  likely,  of  their  own  motion,  to  do  anything  toward 
a  different  disposal  of  the  sewage,  as  all  other  methods  involve 
additional  expense.  Riparian  owners,  especially  when  they  have 
located  manufactories  for  the  sake  of  the  conveniences  which 
the  stream  affords,  will  not,  as  a  rule,  adopt  any  method  for  dis- 
posing of  their  sewage  or  manufacturing  refuse  which  involves 
expense,  unless  compelled  to  do  so.  Even  where  waste  material 
may  be  utilized,  so  that  the  expense  is  met  by  a  corresponding 
return,  the  vis  inertice  is  so  great  that  legal  pressure  is  generally 
necessary  to  secure  the  adoption  of  plans  which,  in  the  end,  may 
prove  as  advantageous  to  the  manufacturer  as  to  his  previously 
injured  neighbor. 

The  following  is  a  very  brief  summary  of  the  legal  restric- 
tions which  exist  in  several  European  States  :  * 

"  In  Prussia;  though  there  are  no  special  regulations  for  the 
inspection  of  factories  in  order  to  prevent  the  pollution  of  run- 
ning waters,  there  are  very  simple  means  of  interference  in  every 
separate  case  of  pollution  by  manufacturing  refuse.  Thus,  by 
the  statute  of  July  I,  1861,  most  of  the  processes  which  are 
likely  to  pollute  water  require  a  special  police  license  ;  and  by  a 
statute  passed  as  far  back  as  1843,  no  water  applied  to  dyeing, 
tanning,  fulling,  or  other  similar  purposes,  is  to  be  suffered  to 
enter  a  river,  if  thereby  the  means  of  procuring  clean  water  be 
endangered  to  the  neighborhood  ;  and  by  a  regulation  dating 
from  October  28,  1846,  the  owners  of  such  works  as  impregnate 
the  water  used  in  any  manufactory,  with  materials  hurtful  to 
meadow  land,  must,  in  accordance  with  the  judgment  and  direc- 
tion of  the  police  authorities,  precipitate  their  materials  in  sub- 
sidence ponds,  or  otherwise,  under  penalty  of  fine. 

"  In  Belgium  there  are  various  local  regulations,  having  the 
force  of  law,  which  impose  a  penalty  upon  those  who  pollute 
rivers,  either  by  throwing  in  solid  materials,  which  may  impede 
the  course  of  the  stream,  or  by  allowing  liquid  matter,  which  may 
foul  or  corrupt  the  water,  to  flow  into  it.  Manufactories  which 
produce  such  refuse  are  bound  to  construct  reservoirs  sufficiently 
large  to  contain  a  day's  supply  of  this  refuse,  in  order  that  suf- 

*  Rivers  Pollution  Commission.     First  Report  1870,  p.  42. 


PREVENTION  OF   POLLUTION.  73 

ficient  settlement  may  take  place,  and  the  supernatant  liquid  only 
is  allowed  to  be  run  off." 

In  France,  several  royal  ordinances  and  decrees  of  the  Coun- 
cil (1669,  1672,  1773,  1777,  1783),  forbid  the  pollution  of  streams. 
All  of  these  ordinances  and  decrees,  which  still  have  the  force  of 
law,  prohibit,  under  penalty,  casting  into  the  Seine  or  into  other 
water-courses,  "  aucunes  ordures,  imnwndices,  gravois,  pailles  et 
fumiers"  The  laws  of  December  22,  1789,  and  August  16-24, 
1790,  grant  to  departmental  and  municipal  authorities  power  to 
preserve  the  purity  of  streams,  and  to  interpose  if  the  waters 
become  a  source  of  ill-health.  A  ministerial  decision,  dated  July 
24,  1875,  reaffirms,  in  principle,  the  decrees  of  1773  and  1777.* 

That  the  laws,  even  of  well-policed  countries  like  Germany 
and  France,  do  not  succeed  in  wholly  accomplishing  the  object 
desired,  is  evident  from  the  present  condition  of  certain  streams, 
notably  of  the  Seine  and  Spree.  In  England,  there  were  formerly 
laws  similar  to  those  existing  in  France  ;  but  the  enormous  de- 
velopment of  the  manufacturing  industry  in  that  country,  and 
the  national  sensitiveness  as  to  the  liberty  of  the  subject,  served, 
in  course  of  time,  to  render  them  all  dead  letters. 

The  Public  Health  Act,  of  1848,!  gave  local  authorities  power 
to  build  sewers  and  discharge  them  into  streams  wherever  they 
saw  fit.  Then  began,  on  a  large  scale,  the  pollution  of  the  rivers 
of  the  country  which  has  since  become  so  great  an  evil.  By  the 
Nuisances  Removal  Act,  1855,  provision  was  first  made  for  en- 
joining individuals,  towns  and  corporations  against  the  pollution 
of  streams.  To  provide  for  the  full  carrying  out  of  the  require- 
ments of  the  act,  Section  IX  contains  a  clause  that  the  local 
authorities  shall  appoint  or  employ  a  sanitary  inspector  or  in- 
spectors. In  1858,  local  authorities  were  rendered  liable  to 
injunction  for  polluting  streams. 

In  the  Sewage  Utilization  Act  of  1865,  we  find  this  clause; 
"  Nothing  contained  in  this  act  or  any  other  acts  referred  to 
therein  (i.  e.,  all  the  sanitary  acts  previously  passed),  shall  author- 
ize any  sewer  authority  to  make  a  sewer  so  as  to  drain  direct  into 
any  stream  or  water-course."  By  the  same  acts  the  powers  of 
sewer  authorities  were  extended  as  to  the  pollution  of  streams. 

*  Schlcesing  et  Durand-Claye.     Rapport. 

f  This  sketch  of  English  legislation  is  condensed  from  the  Seventh  Annual 
Report  of  the  Mass.  State  Board  of  Health. 


74  WATER  SUPPLY. 

Seventeen  years  had  sufficed  to  reverse  entirely  the  laws  on  the 
subject.  In  1848,  towns  were  urged  to  empty  sewage  freely  into 
the  most  convenient  water-courses. 

The  first  Rivers  Pollution  Commission  was  appointed  in  1865  ; 
the  second  was  appointed  in  1868,  and  their  last  report  (the  sixth), 
was  printed  in  1874.  Largely  as  a  result  of  the  careful  and  com- 
prehensive investigations  of  these  commissions,  and  especially  of 
the  second  one,  there  was  passed,  in  1876,  a  Rivers  Pollution 
Prevention  Act,*  which  was  certainly  a  great  step  in  advance, 
although  the  act  is  not  satisfactory  to  sanitarians  in  all  respects. 
The  provisions  of  the  act  are,  briefly,  as  follows :  f 

I.  Prohibition  as  to  casting  solid  matter  (ashes,  dead  animals, 
etc.)  into  water-courses. 

II.  Prohibition    as   to    casting    sewage   proper   into    water- 
courses.    In  case,  however,  of  sewage  discharged  by  channels  in 
use  or  process  of  construction  at  the  date  of  passage  of  the  act, 
it  will  be  sufficient  to  show  that  the  best  practicable  and  avail- 
able means  are  used  to  render  harmless  the  sewage  so  discharged, 
and  the  Local  Government  Board  may  allow  to  sanitary  author- 
ities time,  in  order  to  adopt  such  means. 

III.  (i)  Prohibition   as    to    casting   poisonous,    noxious,    or 
polluting  refuse  from  manufactories  into  water-courses,  with  the 
same  provision  as  above  with  regard  to  channels  already  in  use 
or  in  process  of  construction.    Proceedings  against  manufactories 
can  be  taken  only  by  consent  of  the  Local  Government  Board, 
who  must  be  satisfied   that  means  for  rendering  the  manufactur- 
ing refuse  harmless   are    reasonably    practicable  and   available, 
under  all  the  circumstances  of  the  case,  and  that  no  material 
injury  will  be  inflicted  upon  the  interests  of  the  manufacturers. 

(2)  Restrictions  as  to  solid  matter  from  mines. 

The  following  definition  was  formulated  by  the  Rivers  PoL 
lution  Commission  (1868)  of  liquids  which  should  be  deemed 
polluting  and  inadmissible  into  any  stream,  but  they  have  not 
been  established  by  legal  enactment. 

(a)  Any  liquid  which  has  not  been  subjected  to  perfect  rest 
in  subsidence  ponds  of  sufficient  size  for  a  period  of  at  least  six 
hours,  or  which  having  been  so  subjected  to  subsidence,  contains 

*  The  text  of  this  act  may  be  found  in  the  Eighth  Annual  Report  of  the  Mass. 
State  Board  of  Health,  p.  73. 

f  Quoted  from  Ninth  Annual  Report  of  the  Mass.  State  Board  of  Health. 


PREVENTION  OF  POLLUTION.  75 

in  suspension  more  than  one  part  by  weight  of  dry  organic 
matter  in  100,000  parts  by  weight  of  the  liquid,  or  which,  not 
having  been  so  subjected  to  subsidence,  contains  in  suspension 
more  than  three  parts  by  weight  of  dry  mineral  matter,  or  one 
part  by  weight  of  dry  organic  matter  in  100,000  parts  by  weight 
of  the  liquid. 

(fr)  Any  liquid  containing,  in  solution,  more  than  two  parts 
by  weight  of  organic  carbon  or  0.3  part  by  weight  of  organic 
nitrogen  in  100,000  parts  by  weight. 

(c)  Any  liquid  which  shall  exhibit  by  daylight  a  distinct  color 
when  a  stratum  of  it  one  inch  deep  is  placed  in  a  white  porcelain 
or  earthenware  vessel. 

(d)  Any  liquid  which  contains  in  solution,  in  100,000  parts 
by  weight,  more  than  two  parts  by  weight  of  any  metal  except 
calcium,  magnesium,  potassium,  and  sodium. 

(e)  Any  liquid  which  in  100,000  parts  by  weight    contains, 
whether  in  solution  or  suspension,  in  chemical  combination  or 
otherwise,  more  than  0.05  part  by  weight  of  metallic  arsenic. 

(/)  Any  liquid  which,  after  acidification  with  sulphuric  acid, 
contains,  in  100,000  parts  by  weight,  more  than  one  part  by 
weight  of  free  chlorine. 

(g)  Any  liquid  which  contains,  in  100,000  parts  by  weight, 
more  than  one  part  by  weight  of  sulphur,  in  the  condition  either 
of  sulphuretted  hydrogen  or  of  a  soluble  sulphuret. 

(//)  Any  liquid  possessing  an  acidity  greater  than  that  which 
is  produced  by  adding  two  parts  by  weight  of  real  muriatic  acid 
to  i  ,000  parts  by  weight  of  distilled  water. 

(t)  Any  liquid  possessing  an  alkalinity  greater  than  that  which 
is  produced  by  adding  one  part  by  weight  of  dry  caustic  soda  to 
1 ,000  parts  by  weight  of  distilled  water. 

(k)  Any  liquid  exhibiting  a  film  of  petroleum  or  hydrocarbon 
oil  upon  its  surface,  or  containing  in  suspension,  in  100,000 
parts,  more  than  0.05  part  of  such  oil. 

To  these  standards  was  attached  the  proviso,  that  "  no 
effluent  water  shall  be  deemed  polluting  if  it  be  not  more 
contaminated  with  any  of  the  above-named  polluting  ingredients 
than  the  stream  or  river  into  which  it  is  discharged." 

In  this  country  comparatively  little  has  been  done  in  the  way 
of  legislation  from  a  sanitary  point  of  view,  as  the  polluted 
streams  are  still  few  in  number,  and  the  necessity  for  legislation 


76  WATER  SUPPLY. 

has  not  become  pressing.  In  some  States  there  are  general  laws 
against  the  obstruction  and  pollution  of  water-courses,  or  special 
provision  for  securing,  to  a  certain  extent,  the  purity  of  streams 
or  other  waters  actually  used  as  sources  of  supply. 

In  the  District  of  Columbia  there  is  a  law  of  the  United 
States  (1859),  which  provides  penalty  for  committing  any  act  by 
reason  of  which  the  supply  of  water  to  the  cities  of  Washington 
and  Georgetown  becomes  impure,  filthy,  or  unfit  for  use.  In 
Iowa,  by  an  act  of  1864,  it  is  punishable  by  fine  or  imprison- 
ment to  throw  any  dead  animal  into  any  river,  well,  spring, 
cistern,  reservoir,  stream,  or  pond.  In  Michigan,  an  act  of  1865 
prohibits  the  putting  of  offal,  etc.,  into  waters  where  fish  are 
taken.  In  Nebraska,  by  act  of  1873,  there  are  penalties  for 
putting  carcasses  or  other  filthy  substances '  into  well,  spring, 
brook,  or  any  running  water  of  which  use  is  made  for  domestic 
purposes  ;  the  corrupting  of  any  water-course  is  declared  to  be 
a  nuisance. 

In  -Tennessee,  by  act  of  1866-7,  rendering  water  unwhole* 
some  is  declared  a  nuisance.  In  Vermont,  by  act  of  1852,  a 
penalty  was  enacted  against  any  one  putting  any  dead  animal 
or  animal  substance  into  rivers,  ponds,  springs,  etc.  In  Wis- 
consin there  are  laws  providing  against  the  erection  of  slaughter- 
houses on  the  banks  of  any  river,  stream  or  creek,  or  throwing 
any  carcass  or  offal  therefrom  in  or  upon  the  bank  of  any  such 
river,  etc.  In  Texas,  by  act  of  1860,  polluting  or  obstructing 
any  water-course,  lake,  pond,  marsh,  or  common  sewer,  or  con- 
tinuing such  obstruction  or  pollution,  so  as  to  render  the  same 
unwholesome  or  offensive  to  the  county,  city,  town,  or  neighbor- 
hood thereabouts,  or  doing  any  other  act  or  thing  that  would  be 
deemed  and  held  a  nuisance  at  common  law,  is  made  a  misde- 
meanor.* 

The  Texas  law,  just  alluded  to,  indicates  very  well  what  is 
generally  the  character  and  effect  of  legislation  on  this  subject. 
If  any  person  or  corporation  pollutes  a  stream  in  such  a  way 
that  the  result  would  be  held  a  nuisance  at  common  law,  or  if 
the  pollution  is  so  great  that  it  can  be  absolutely  proved  that 
water,  which  is  taken  for  domestic  use,  has  become  "  impure, 


*  These  facts  are  gathered  from  "  A  Digest  of  American  Sanitary  Law,  by  Henry 
G.  Pickering,  Esq.,"  in  Dr.  Bowditch's  Public  Hygiene  in  America.    Boston,  1877. 


PREVENTION  OF  POLLUTION.  77 

filthy,  or  unfit  for  use,"  it  is,  under  such  circumstances,  possi- 
ble in  some  cases  to  obtain  an  injunction  against  the  offending 
parties.  But  to  absolutely  prove  that  a  water  is  impure,  filthy 
or  unfit  to  use,  is  difficult  unless  one  can  present  in  court  the 
body  of  some  person  who  has  died  by  the  use  of  the  water ; 
and,  according  to  certain  decisions  which  have  been  made,  it 
would  seem  that  nothing  short  of  this  will  suffice.  In  several 
States  a  local  or  a  State  Board  of  Health  has  some  powers  in 
these  matters,  but  they  are  mostly  nominal  and  rendered  of  no 
avail  by  rights  of  appeal.  A  great  deal  of  attention  has  been 
given  to  the  pollution  of  streams  in  the  State  of  Massachusetts, 
and  the  two  following  sections  from  chap.  183  of  the  Acts  of  1878 
would  seem  sufficiently  explicit : 

"  Section  i.  No  person  or  persons,  or  corporation,  public 
or  private,  shall  discharge  directly,  or  cause  to  be  discharged 
directly,  human  excrement  into  any  pond  in  this  Commonwealth 
used  as  a  source  of  water  supply  by  any  city  or  town  therein,  or 
upon  whose  banks  any  filter-basin  so  used  is  situated,  or  into 
any  river  or  stream  so  used,  or  upon  whose  banks  such  filter- 
basin  is  situated,  within  twenty  miles  above  the  point  where  such 
supply  is  taken,  or  into  feeders  of  such  ponds,  river  or  stream 
within  such  twenty  miles. 

"  Section  2.  No  person  or  persons,  or  corporation,  public  or 
private,  shall  discharge,  or  cause  to  be  discharged,  into  any 
pond  in  this  Commonwealth  used  as  a  source  of  water  supply  by 
any  city  or  town  therein,  or  upon  whose  banks  any  filter-basin 
so  used  is  situated,  or  into  any  river  or  stream  so  used,  or  upon 
whose  banks  such  filter-basin  is  situated,  within  twenty  miles 
above  the  point  where  such  supply  is  taken,  or  into  any  feeders 
of  such  pond,  river,  or  stream  within  such  twenty  miles,  any  sew- 
age, drainage,  refuse,  or  polluting  matter  of  such  quality  and 
amount,  as  either  by  itself,  or  in  connection  with  other  such  matter, 
shall  corrupt  or  impair  the  quality  of  the  water  for  domestic  use, 
or  render  it  deleterious  to  health."  * 

It  would  seem  that  these  provisions  would  give  all  necessary 
security,  but  two  practical  difficulties  occur.  Section  3  reads  as 
follows  : 

"The  prohibitions  contained  in  the  two  previous  sections 
shall  not  be  construed  to  destroy  or  impair  rights  already  ac- 

*  The  italics  are  the  author's, 


78  WATER   SUPPLY. 

quired  by  legislative  grants,  or  to  destroy  or  impair  prescriptive 
rights  of  drainage  or  discharge,  to  the  extent  to  which  they 
lawfully  exist  at  the  date  of  the  passage  of  this  act :  And  nothing 
in  this  act  contained  shall  be  construed  to  authorize  the  pol- 
lution of  any  waters  in  this  Commonwealth  in  any  manner  now 
contrary  to  law. 

"  This  act  shall  not  be  applicable  to  the  Merrimack  or  Con- 
necticut rivers,  nor  to  so  much  of  the  Concord  River  as  lies 
within  the  limits  of  the  city  of  Lowell." 

The  deciding  whether  a  prescriptive  right  exists  is  not  always 
easy,  but  the  chief  difficulty  lies  in  the  fact  that  while  the  State 
Board  of  Health  is  given  the  power  to  issue  orders  "  to  cease 
and  desist,"  the  parties  have  a  right  of  appeal  to  jury.  This 
jeopardizes  the  whole  matter  at  once,  and,  as  the  pollution 
often  takes  place  in  one  county  to  the  detriment  or  supposed 
detriment  of  water-users  in  another  county,  the  jury  are  apt  to 
be  influenced  by  local  interests. 

While  it  must  be  confessed  that  the  present  state  of  legisla- 
tion is  unsatisfactory,  it  must  be  admitted  that  it  is  practically 
impossible  absolutely  to  prevent  the  pollution  of  streams,  and  it 
will  probably  always  be  necessary  that  certain  streams  should 
serve  as  carriers  of  refuse.  At  the  same  time,  the  amount  of 
pollution  should  be  kept  within  bounds,  so  that  the  water, 
although  it  may  not  be  fit  or  safe  for  domestic  use,  shall  not  be 
an  actual  nuisance ;  while  some  streams  are  thus  devoted  to  viler 
uses,  those  which  are  reserved  for  purposes  of  water  supply 
should  be  guarded  with  all  possible  care.  It  is  evident  that 
nothing  is  more  unphilosophical  than  that  one  town  should  be 
allowed  to  discharge  its  sewage  into  a  water-course  which  is  the 
most  available  source  of  water  supply  for  a  town  lower  down  on 
the  stream.  Each  river  basin  should  be  under  the  control  of 
some  central  authority  by  which  conflicting  interests  should  be 
harmonized;  An  accurate  survey  should  be  made  of  the  whole 
area,  and  no  town  should  be  allowed  to  introduce  a  water  sup- 
ply without  due  consideration  being  given  to  the  future  of  the 
supply,  and  to  the  question  of  disposing  of  the  sewage  of  the 
town  supplied.  Moreover,  while  sanitary  considerations  are  of 
the  highest  importance,  manufacturing  interests  must  also  be 
considered,  and  no  undue  burden  laid  upon  legitimate  indus- 
tries. 


CHAPTER    V. 


SURFACE  WATERS  AS   SOURCES   OF   SUPPLY.      (Continued^) 
Animal  and  Vegetable  Life. 

No  surface  water  is  free  from  various  forms  of  animal  and 
vegetable  life ;  it  is  seldom,  however,  that  any  trouble  arises  from 
this  cause  when  the  water  is  taken  directly  from  running  streams. 
On  the  other  hand,  the  water  in  lakes  and  ponds  and  in  storage 
reservoirs  is  extremely  liable  to  be  disagreeably  affected  by  the 
growth  and  decay  of  animal  and  more  especially  of  vegetable 
organisms. 

Animals. — The  presence  of  fish  in  a  source  of  supply  is  an 
advantage  rather  than  otherwise.  As  far  as  known,  any  trouble 
arising  from  their  presence  is  quite  temporary  and  accidental. 
The  sudden  discharge  into  a  stream  of  material  injurious  in  itself, 
or  which,  by  using  up  the  oxygen  of  the  water,  makes  it  impos- 
sible for  the  fish  to  breathe,  may  cause  their  destruction  in  large 
numbers.  Occasional  epidemics,  in  some  cases  due  to  fungous 
growths,  may  affect  large  numbers  of  fish  at  the  same  time.  In 
such  cases,  the  sources  of  supply  must  be  watched  and  the  dead 
fishes  removed  as  thoroughly  and  as  rapidly  as  possible. 

Among  the  smaller  forms  of  animal 
life  we  have  the  so-called  water-fleas,  of 
which  the   Daphnia  pulex   (Fig.   6)    and 
the  Cyclops  quadricornis  (Fig.  7)  are  fa- 
miliar   examples.      These  or 
other  similar  animalcules 
swarm  in  many  surface  waters 
at  certain  seasons  of  the  year, 
and  occur  more  or  less  abun- 
dantly in  all  pond  and  river 

waters.     They  no  doubt,  to  a 

...      FIG.  6. — Daph 
certain  extent,  tend  to  purify       niapuiex. 


FIG.  7. — Cyclops  quadri- 
cornis. 


the  water  by  removing  objec- 
tionable substances,  and  are  in  turn  devoured  by  other  animals. 


8O  WATER   SUPPLY. 

They  are  easily  removed  by  the  simplest  sort  of  filtration,  but 
there  is  no  probability  that  they  are  unwholesome  if  taken  with 
the  water.  These  minute  crustaceans  secrete  an  oily  substance 
under  their  shells  (carapaces)  which  some  have  held  to  be  the 
cause  of  certain  bad  tastes  which  have  affected  water  supplies, 
but  it  is  extremely  doubtful  if  this  is  a  correct  explanation  of 
the  trouble.  It  may  be  said,  however,  that  a  fishy  odor  has  been 
frequently  noticed  on  the  Lake  of  Geneva,  very  perceptible  to 
the  passengers  on  the  passing  steamboats,  occasionally  over  the 
entire  lake.  This  odor  is  ascribed  by  Dr.  F.  A.  Forel  *  to  an 
unusual  mortality — from  some  unknown  cause — among  the  en- 
tomostraca  which  swarm  in  the  lake,  and  which  usually  by  day 
descend  to  a  depth  of  5>  10,  or  20  meters,  rising  to  the  surface  at 
night.  It  is  possible  that  some  of  the  temporary  bad  tastes  in 
surface  waters  may  be  due  to  a  similar  cause. 

In  1 88 1,  a  portion  of  the  water  supply  of  Boston,  Mass.,  was 
in  a  very  bad  condition.  The  water  contained  an  unusual 
amount  of  organic  matter  and  possessed  a  very  disagreeable 
odor  and  taste.  This  bad  condition  of  the  water  was  found  by 
Professor  Remsen,f  to  be  mainly  due  to  the  presence  in  one  of 
the  reservoirs  of  a  large  quantity  of  a  Spongilla,  or  fresh-water 
sponge,  in  a  more  or  less  decayed  condition.  Several  species  of 
the  fresh-water  sponge  occur  in  ponds  and  streams,  and  they 
are  found  even  in  the  masonry  conduits  to  a  limited  distance 
from  the  source  of  supply.  The  following  cut  will  give  a  fair 
idea  of  the  general  appearance  of  the  Spongilla  fluviatilis,  al- 
though the  details  are  somewhat  unsatisfactory.  The  sponge 
belongs  to  the  animal  kingdom,  and  the  animal  substance  is  dis- 
tributed over  a  network  of  spicules.  No.  2  in  the  figure  at- 
tempts to  show  some  of  the  "winter  buds,"  or  bodies  by  which 
the  animal  is  propagated,  held  in  a  mass  of  spicules ;  No.  3  is  a 
portion  of  the  same  enlarged.  The  sponge  is  harsh  to  the  touch, 
and  with  a  good  lens  something  of  its  structure  may  be  made 
out ;  for  confirmation,  however,  it  is  well  to  burn  off  a  little  on 
"a  fragment  of  mica,  moisten  with  water  (or  better,  with  acid, 
muriatic  acid  or  dilute  aqua  fortis)  and  examine  with  a  good  lens 


*  Private  communication. 

f  Report  of  the  Joint  Standing  Committee  on  the  Impurity  of  the  Water  Supply. 
Boston  City  Document,  No.  143,  1881. 


ANIMAL  AND   VEGETABLE   LIFE. 


8l 


or  a  low-power  microscope  (say  from  50  to  100  diameters)  for  the 
spicules.  The  larger  spicules,  which  are  observed  by  examining 
with  a  low  power  the  sponge  of  the  Boston  water  supply,  appear 
as  in  Fig.  9  (drawn  with 
a  power  of  about  1 50  di- 
ameters). Other  spic- 
ules are  covered  with 
short  spines,  and  the  so- 
called  winter-buds,  by 
which  the  sponge  is 
propagated,  are  furnish- 
ed with  minute  spicules 
which  are,  in  certain 
species,  very  character- 
istic :  thus  in  5.  fluviat- 
ilis  they  are  birotulate, 
as  shown  in  Fig.  10,  a. 
Some  of  the  smaller 
spicules  of  the  sponge 
which  occurs  in  the  Bos- 
ton water  are  shown  in 
Fig.  10,  b  and  c.  Fig. 
10  was  drawn  with  a 
power  of  about  260  di- 
ameters.  i 

Although  the  spon-  \ 
ges  have  caused  trouble 
in  Boston  and  perhaps 
elsewhere,  the  fact  that 
they  exist  in  a  water 
supply  need  not  neces- 
sarily awaken  appre- 
hension. They  prob- 
ably exist  in  nearly 

all  surface  waters,  and  the  spicules  are  among  the  common 
objects  found  by  a  microscopic  examination  of  the  sediment 
in  natural  waters.*  According  to  Dr.  R.  D.  Thompson,  the 

*  See  for  example:,  the  plates   in    Hassall's    Microscopical  Examination   of  the 
Water  supplied  to  the  Inhabitants  of  London  and  the  Suburban  Districts.    London, 
1851.     Also,  Neuville,  Des  Eaux  de  Paris.     Paris,  1880. 
6 


FIG.   8. — Spongilla  fluviatilis* 


82 


WATER   SUPPLY. 


dried  Spongilla  fluviatilis  contains  26  per  cent  of  organic  matter. 

This  organic  matter  is  highly  nitrogenous,  although  no  particular 

analyses  seem  to  have 
been  made  of  the  fresh  wa- 
ter sponges.  The  tissue- 
substance  of  salt  water 
sponges — fibroin  (Mulder) 
or  spongin  (Stadeler) — 
has  the  following  compo 
sition  : 


Posselt. 

Crookewit  . 

Carbon.  .  .  . 

48.75 

47.16 

Hydrogen  . 

6-35 

6.3I 

Nitrogen  .  . 

16.40 

16.15 

Oxygen  .  .  . 

28.50 

26.90 

Iodine 

1.  08 

Sulphur  .  .  . 

.... 

0.50 

Phosphorus 

.... 

I.90 

FiG  9. — Sponge  spicules. 


100.00  ICO. 00 


Among  the  other  forms  of  animal  life  which  may  be  here 
mentioned,  is  the  Hydra,  which  is  common  enough  in  ponds, 
adhering  to  aquatic  plants.  The  body  is  narrow  and  elongated ; 
it  is  generally  attached 
by  the  base  to  some 
plant  or  other  solid  ob- 
ject while  the  other  ex- 
tremity of  the  body  is 
furnished  with  long  slen- 
der arms  or  tentacles, 
which  move  about  in 
search  of  the  animalcules 
on  which  it  feeds.  It 
may  be  worth  while  to 
mention  the  fact  that  in 
a  conduit  where  a  gate- 
house admits  access  to 
the  interior,  the  author 

has  seen  the  rapidly  flow-  FlG"  ">.-#*«** 

ing  water  swarming  with  these  creatures,  so  that,  in  dipping 
up  a  single  glass  of  water,  a  dozen  or  twenty  of  the  hydras 
would  be  taken  at  the  same  time.  On  the  bottom  and  sides 


ANIMAL  AND   VEGETABLE    LIFE.  83 

of  the  conduit  were,  no  doubt,  hundreds  of   thousands  of   the 

little  animals,  but  no  recogniz- 
able effect  was  produced  on  the 
water  by  their  presence  or  by 
their  death  and  decay,  which 
must  have  followed. 

Of  course  there  are  many 
other  animal  inhabitants  of  fresh 
waters,  and  when  we  descend  to 
microscopic  organisms  we  have 
a  very  great  variety  of  forms. 
The  term  Infusoria  is  often  used 

FIG.  ii. — Hydra  viridis.  ..     .  .  * 

to  cover  all  these  minute  animal 

organisms,  which  are  grouped  under   orders   and    families   and 
genera  and  species  like  the  higher 
animals.      Scarcely   any  natural 
water  is  free  from  these  infusoria, 
and  some  of  them  are  peculiar  to 
impure  waters,  but,  as  they  can 
be  recognized  and  studied  only 
under  the  microscope  by  those  familiar  with 
such  matters,  we  need  not  dwell  upon  them 
here. 

Plants. — Generally  speaking,  the  flowering 
aquatic  plants,  such  as  are  known  as  eel-grass, 
pond-weed,  pickerel-weed,  etc.,  are  in  them- 
selves of  no  disadvantage,  while  growing,  to  the 
pond  or  reservoir  in  which  they  grow  ;  they  are, 
indeed,  of  positive  advantage,  in  oxygenating, 
and  so,  to  a  certain  extent,  purifying  the  water. 
If  such  plants,  or  portions  of  them,  decay  in  a 
limited  volume  of  water  they  produce  a  very  of- 
fensive smell  and  taste.  This  is,  in  general,  true 
of  plants  aquatic  and  non-aquatic.  It  is  well 
known  that  the  water  in  which  flax  is  "  retted  " 
becomes  very  offensive.*  In  some  experi- 
ments made  by  the  author  a  few  years  ago,  FlG'  I2--p°nd-weed 

.  „      ,       .        ,  '  (Potamogeton). 

the  worst  smell  obtained  was  from  the  seed- 

*  In  this  connection  see  Reichardt,  E.,  "  Schadliche  Wirkung  des  Rostwassers 
von  Flachs  und  Hanf  fur  die  Fischzucht."     Arch.  d.  Pharm.,  ccxix,  Heft  I,  1881. 


84  WATER   SUPPLY. 

bearing  portions  of  a  species  of  Potamogeton  (a  common  water 
plant),  and  Professor  Brewer,  who  has  made  much  more  exten- 
sive experiments,  obtained  a  very  fishy  odor  from  the  decay  in 
water  of  the  leaf-stalks  of  a  pickerel-weed,  Pontedcria  cordata, 
which  grows  on  the  margins  of  the  pond  from  which  New  Haven 
receives  its  supply  (Whitney  Lake). 

While  the  odors  and  tastes  obtained  from  different  plants 
differ  from  each  other,  in  a  stream  or  pond  where  the  volume 
of  water  is  comparatively  large  and  the  opportunity  for  aeration 
is  great,  the  various  tastes  seem  to  blend  into  a  more  or  less 
marked  marshy  or  pondy  flavor.  Sometimes,  even  in  large  bodies 
of  water,  a  distinctive  taste  is  noticed ;  thus,  in  the  fall  of  the 
year,  the  water  of  our  ponds  and  lakes  which  are  surrounded  by 
woods  acquires  more  of  a  bitter  or  astringent  taste,  which 
is  to  be  referred  to  the  dead  leaves  at  that  season  most 
abundant. 

A  word  or  two  may  be  in  place  with  reference  to  the  action 
of  fresh  water  upon  vegetable  matter  in  its  bearing  upon  im- 
pounding reservoirs.  When  vegetable  matter  decays  in  moist 
soil,  it  is  converted  into  a  brown  or  black  substance  generally 
known  as  humus ;  this  is  really  a  mixture  of  a  number  of  differ- 
ent bodies,  and  from  it  chemists  have  isolated  a  variety  of  sub- 
stances, such  as  humic  acid  and  humin,  ulmic  acid  and  ulmin.* 
The  acids  of  the  humus,  by  oxidation,  undergo  chemical  change, 
to  be  sure,  being  converted  into  crenic  and  apocrenic  acids, 
which,  or  rather  the  salts  of  which,  are  found  in  surface  waters  ; 
but  when  the  vegetable  matter  is  thoroughly  "  humified,"  as  in 
the  case  of  peat,  it  exerts  apparently  no  bad  effect  on  the  water, 
except  by  giving  it  a  brown  color  and  a  somewhat  earthy  taste. 

When  a  recently  felled  tree  is  exposed  to  the  action  of  the 
water,  or  when  bushes  or  even  grass  and  weeds  are  killed  by  being 
flooded  with  water,  the  sap  and  more  soluble  matters  are  leached 
out  and  putrefy,  or,  in  the  presence  of  much  air,  undergo  other 
forms  of  decomposition.  This  action  will  take  place,  no  mat- 
ter under  what  depth  of  water  the  vegetable  matter  may  be 
placed,  but  the  effect  will  be  less  marked  as  the  amount  and 
motion  of  the  water  is  greater. 

*  For  a  resume  of  the  investigations  on  the  composition  of  humus,  see  Julien : 
Proc.  Amer.  Assoc.,  xxviii  (1879),  p.  313  and  foil. 


ANIMAL  AND   VEGETABLE   LIFE.  8$ 

After  the  more  soluble  portions  are  extracted,  the  subsequent 
decay  proceeds  with  extreme  slowness,  provided  the  remaining 
cellulose  or  woody  fiber  is  kept  continually  covered  with  water, 
but  alternate  exposure  to  air  and  water  soon  causes  decay,  as 
every  one  knows.  In  a  natural  or  artificial  reservoir  the  inevita- 
ble variations  of  level  are  very  disadvantageous.  As  the  level  is 
lowered,  those  aquatic  plants  which  grow  in  shallow  water  die, 
and  if  the  water  rises  after  only  a  short  interval  it  becomes 
impregnated  with  the  products  of  their  decay ;  if  a  considerable 
interval  elapses,  land  plants  grow  upon  the  exposed  surface,  and, 
being  drowned  by  the  rising  waters,  tend  to  its  contamination  in 
the  same  manner. 

It  appears  from  this,  that  in  the  construction  of  impounding 
reservoirs,  the  mass  of  growing  plants,  as  well  as  the  soil  in 
which  they  have  their  roots,  and  which  of  itself  contains  more  or 
less  soluble  organic  matter,  should  be  removed  as  thoroughly  as 
possible,  especially  if  the  water  is  to  be  of  no  great  depth  above 
it  when  the  reservoir  is  flooded.  If  the  reservoir  is  filled  with- 
out such  removal  of  the  organic  accumulations,  a  long  time  may 
may  be  required  before  the  chemical  changes  have  completed 
themselves  and  the  water  become  well  suited  for  use,  but  the 
complete  removal  of  the  soil,  that  is,  as  far  as  such  removal  is 
practicable,  is  not  a  guaranty  that  no  trouble  will  arise  from  a 
newly  filled  reservoir.  Occasionally  the  vegetable  decay  in  a 
new  reservoir  gives  rise  to  much  offence  from  the  formation  of 
sulphuretted  hydrogen.  A  marked  instance  of  this  occurred 
in  one  of  the  basins  of  the  Sudbury  River  supply,  Boston, 
Mass.,  the  summer  after  it  was  first  filled.  The  whole  mass  of 
water  in  the  basin  was  permeated  with  the  odor,  which  was  so 
strong  on  the  leeward  side  of  the  pond  as  to  incommode  the 
passers-by.  The  odor  was  not  that  of  pure  sulphuretted  hydro- 
gen as  prepared  in  the  laboratory,  and  the  gas  was  no  doubt  ac- 
companied by  other  chemical  products.  The  water  drawn  from 
the  depths  of  the  pond  had  the  odor  of  an  antiquated  privy. 
The  presence  of  sulphuretted  hydrogen  was  made  very  manifest 
by  suspending  in  the  gate-house  cloths  wet  with  a  solution  of 
acetate  of  lead  ;  these  became  yellowish-red,  and  finally  jet  black, 
owing  to  the  formation  of  sulphide  of  lead. 

The  formation  of  the  sulphuretted  hydrogen  is  readily  ex- 
plained. The  flooding  of  the  basin  started  the  decay  of  a  large 


86 


WATER   SUPPLY. 


quantity  of  organic  matter ;  this  taking  place  in  the  presence  of 
the  sulphates  contained  in  the  water  changed  them  into  sulph- 
idesy  and  from  these  sulphides  thus  formed  sulphuretted  hydrogen 
is  liberated  by  the  acid  products  of  decay.  This  same  change 
takes  place  to  a  less  degree  in  almost  all  ponds  and  reservoirs. 
The  gas  is  formed,  however,  mainly  at  the  bottom,  and  as  it  dif- 
fuses upwards  and  mixes  with  the  overlying  water  it  comes  into 
contact  with  the  oxygen  in  the  water  and  is  decomposed.  The 
sulphur  is  set  free  and  sinks  to  the  bottom,  or  in  a  very  finely 
divided  state  flows  off  with  the  water.  In  salt  or  brackish  water 
which  receives  sewage,  these  changes  take  place  on  a  much 
greater  scale.  A  while  ago  the  author  had  occasion  to  examine 
a  number  of  samples  of  mud  from  the  lower  part  of  the  Charles 
River,  a  tidal  stream  which  receives  a  portion  of  the  sewage  of 
Boston,  Mass.  In  all  cases  sulphur  in  considerable  quantity 
could  be  extracted  from  the  mud  by  the  use  of  proper  solvents.* 
The  plants  which  give  the  most  trouble  in  connection  with 
water  supplies  belong  to  the  class  of  cryptogamous  (non-flower- 
ing) plants  which  the  botanists  call  alga — plants  which  grow  in  the 
water,  or  in  moist  places,  and  usually  contain  chlorophyll  (green 

coloring  matter)  or  some 
allied  substance.  Not 
all  algae  are,  however, 
harmful.  The  so-called 
confervoid  growths  are 
made  up  of  plants  of  fila- 
mentous structure,  grass- 
green,  or  in  some  cases 
bluish-green  in  color, 
forming  tangled  masses 
readily  removed  from 
the  water,  and,  when  so 
removed,  shrinking  enor- 
mously in  apparent  bulk, 
and  drying  away  to  a 
grayish  or  colorless  mass, 
in  some  cases  looking  al- 
most like  coarse  paper. 


a  c 

FIG.  13. — a,  Diatom  (Stauroneis)  ;  b,  Desmid 
(Euastruni)  ;  c,  Desmid  {Micrasteiias). 


*  Eighth  Annual  Report  Boston  City  Board  of  Health.     (1879-80),  pp.  12-18. 


ANIMAL  AND   VEGETABLE   LIFE.  87 

Plants  of  this  character  grow  in  almost  all  reservoirs  or  other 
bodies  of  water  exposed  to  the  light  and  air,  both  in  still  and 
running  water;  they  either  float  about  in  masses,  or  are  attached 
more  or  less  firmly  to  rocks  and  stones  and  other  solid  objects. 
By  their  growth  they  do  no  harm  to  the  water  in  which  they 
flourish  ;  and  as  they  are  readily  arrested  by  ordinary  wire 
screens,  or  easily  removed  by  rakes  or  scoop-nets,  their  presence 
causes  no  serious  inconvenience  in  water  used  for  town  supply. 

Then  there  are  the  diatoms  and  desmids  (Fig.  13),  which  are 
interesting  objects  under  the  microscope,  and  occur  in  consider- 
able abundance  and  great  variety ;  they  are  not,  however,  as  far 
as  we  know,  of  any  significance  in  surface  waters,  at  least,  from  a 
sanitary  point  of  view. 

The  vegetable  organisms  which  cause  the  most  trouble  and 
inconvenience  are  those  which  appear  as  greenish  specks,  or  mi- 
nute straight  or  curved  threads,  diffused  through  the  water — 
visible  enough  if  a  large  quantity  of  water  be  looked  at,  but  per- 
haps almost  escaping  notice  in  the  small  quantity  which  would 
be  taken  up  in  a  single  glass.  It  is  true  that  the  individual 
plants  are  in  some  cases  distinguishable  by  the  naked  eye  ;  but 
their  form  and  structure  can  be  made  out  only  by  use  of  the 
microscope.  If  collected  together  as  a  scum,  which  often  hap- 
pens, especially  on  the  windward  shore  of  a  pond,  the  scum  is 
not  coherent,  is  easily  broken  up,  either  by  a  wind  setting  in  the 
opposite  direction,  by  a  shower  of  rain,  or  by  artificial  agitation. 
The  appearance  has  been  sometimes  described  as  that  of  meal  or 
of  fine  dust  scattered  through  the  water.  The  number  of  indi- 
viduals is  almost  infinite ;  and  under  favorable  conditions  they 
increase  with  great  rapidity.  Their  presence  gives  a  decidedly 
green  or  greenish  yellow  tinge  to  large  bodies  of  water ;  and 
their  death  and  decay  often  cause  considerable  offence  to  the 
sense  of  smell  of  those  sojourning  in  the  neighborhood,  and  to 
the  sense  of  taste  of  those  obliged  to  drink  the  water.  The 
troublesome  species  belong,  almost  all,  to  the  family  of  Nostocs, 
and  of  these  the  number  which  have  been  known  to  produce 
difficulty  is  small ;  this  may,  of  course  be  due  in  part  to  imper- 
fect observation.  A  single  species  each  of  C&lospk&rium  and 
Clathrocystis,  two  or  more  of  Anabcena  and  one  of  Sphcerozyga 
have  been  observed  in  considerable  quantities  in  the  neighbor- 
hood of  Boston,  Mass. 


88 


WATER   SUPPLY. 


Fig.  14,  c  gives  a  general  idea  of  the  appearance  of  the  Cla- 
throcystis  <zruginosa  when  magnified  some  300  diameters.  This 
plant  is  often  found  in  much  larger  masses  than  indicated  in  the 


FIG.  14. 

cut ;  in  fact,  the  little  sack-like  masses  are  sometimes  large 
enough  to  be  made  out  by  the  unaided  eye,  although  no  idea  of 
the  structure  can  be  thus  obtained.  Fig.  14,  a  attempts  to  give 
an  idea  of  the  Anabczna  circinalis,  one  of  the  Nostochinecz ;  this 
plant  occurs  very  frequently  in  ponds  and  in  sluggish  streams. 
Another  common  variety  of  the  same  genus  is  similar,  except 
that  the  filaments  are  straight  instead  of  curved ;  and  there  are 
other  genera  of  algcz  which  occur  in  the  same  way  as  the  Ana- 
bcena,  and  present  a  similar  appearance. 

These  algae,  when  present  in  any  considerable  quantity,  give 
a  repulsive  appearance  to  the  water,  and  when  they  are  in  a  state 
of  decay  they  communicate  to  it  an  offensive  taste  and  odor. 
Fortunately,  in  most  cases,  the  trouble  which  they  cause  is  of 
short  duration,  although  often  recurring  in  the  same  water  sup- 


ANIMAL  AND   VEGETABLE   LIFE.  89 

ply  year  after  year.  Their  presence  is  not  a  sign  of  contamina- 
tion, as  they  occur  in  natural  ponds  removed  from  all  polluting 
influences.  While,  however,  they  do  grow  in  pure  waters  and  in 
old  and  clean  ponds,  they  seem  to  grow  more  abundantly  in  water 
containing  mud  and  vegetable  extractive  matter,  as  in  newly 
filled  reservoirs  ;  so  that,  while  immunity  from  their  presence 
cannot  be  guaranteed  in  the  case  of  any  pond,  they  may  with 
some  certainty  be  looked  for  in  dirty  and  especially  in  shallow 
ponds.  A  warm  temperature  and  shallow  water  are  perhaps 
of  even  more  importance  than  the  products  of  decay  of  higher 
plants,  for  all  surface  waters  contain  the  ammoniacal  and  mineral 
salts  necessary  for  the  growth  of  the  algae. 

Whether  the  presence  of  these  minute  algae  gives  an  unwhole- 
some character  to  a  water  which  is  otherwise  suited  for  domestic 
use,  is  an  open  question  ;  but  such  information  as  the  author  has 
been  able  to  get  from  various  sources  coincides  with  the  state- 
ment of  the  Mass.  State  Board  of  Health,  who  investigated  the 
matter  when  a  certain  portion  of  the  water  supply  of  Boston  was 
affected  in  this  way.  They  say  *  that  the  evidence  "  tends  to 
show  that  the  plant  acts  mechanically  chiefly,  perhaps  like  unripe 
fruit,  when  affecting  the  health  at  all,  in  causing  diarrhoea ;  but 
that  the  filtered  water  is  harmless."  It  is  known  that  fish  often 
die  in  ponds  containing  an  abundance  of  the  scum-forming  algae, 
probably  on  account  of  the  cutting  off  of  the  supply  of  air  ;  there 
is  also  one  case  on  record  where  cattle  have  been  killed  by  drink- 
ing pond  water  which  contained  large  quantities  of  a  species  of 
Nodidaria,  a  plant  which  has  something  of  a  resemblance  to  the 
Anab<zna.\  This  was  in  Australia.  No  such  cases  have  come  to 
the  knowledge  of  the  writer  here.  When  the  algae  are  alive  and 
fresh,  horses  and  cattle  drink  the  water  readily,  in  preference  to 
spring  water :  when  decay  takes  place,  the  water  sometimes 
becomes  so  offensive  that  they  refuse  to  drink  it.  In  this  condi- 
tion it  is  manifestly  unsuited  for  domestic  use. 

As  far  as  our  present  knowledge  extends,  there  is  nothing 
that  can  be  done  to  exterminate  the  algae  from  ponds  in  which 
they  occur.  Sometimes  in  reservoirs,  when  the  algae  have  col- 
lected as  a  scum,  it  is  possible  to  float  them  off  from  the  surface 

*  First  Annual  Report  of  the  State  Board  of  Health,  Lunacy  and  Charity,  1879. 
Supplement,  p.  xi. 

f  Nature,  xviii  (1878),  p.  n. 


9O  WATER   SUPPLY. 

by  means  of  properly  arranged  waste  pipes,  and  in  reservoirs  the 
conditions  favorable  for  their  collection  and  decay  may  be  re- 
moved by  grubbing  up  the  lilies  and  other  pond-weeds  around  the 
borders.  Special  devices  sometimes  avail  in  special  cases.  The 
experience  at  Poughkeepsie,  N.  Y.,  is  instructive.  Here  the 
Hudson  River  water  was  pumped  on  to  filter-beds,  thence,  after 
filtration,  into  a  small  uncovered  reservoir.  In  summer,  after  the 
temperature  of  the  water  reached  70°  F.,  an  alga,  one  of  the 
oscillariacece,  developed  in  the  shallow  water  on  the  beds  and  in 
the  reservoir,  and  by  its  death  and  decay  in  the  pipes  caused  much 
trouble.  The  trouble  occurred  every  summer,  until  the  following 
method  of  procedure  was  adopted  by  Mr.  The.  W.  Davis,  the 
then  superintendent.  As  soon  as  the  temperature  of  the  river 
water  approached  70°,  careful  watch  was  kept  on  the  temperature 
and  on  the  quality  of  the  water  delivered.  As  soon  as  the  taste 
or  odor  was  noticed  in  the  city,  the  reservoir  was  shut  off  and 
the  water  pumped  directly  from  the  river  into  the  mains.  In 
this  way  all  trouble  was  avoided  and  there  were  no  complaints. 

With  reference  to  the  minute  organisms,  animal  and  vegetable, 
it  is  a  curious  fact  that  certain  forms  will  sometimes  suddenly 
appear  in  places  where  for  years  previous  they  have  never  been 
known  to  occur,  and  they  may  disappear  as  suddenly  as  they 
came.  In  other  cases,  forms  which  have  been  known  to  be  pres- 
ent to  a  limited  extent  will  increase  enormously,  owing  to  con- 
ditions of  which  we  are  quite  ignorant. 

Odors  and  Tastes  of  Surface  Waters. 

Surface  waters  often  possess  peculiar  odors  and  tastes.  These 
are  sometimes  explicable,  as  in  the  case  of  the  odor  of  sulphu- 
retted hydrogen  referred  to  on  page  85.  Then  there  are  other 
odors  (with  accompanying  tastes),  which  are  quite  certainly  due 
to  the  algae.  These  odors  are  quite  various.  Mr.  Fteley  (Sud- 
bury  River)  speaks  of  a  musty  odor  ;  at  Albany  it  was  spoken  of 
as  a  musty  and  cucumber  odor ;  at  Springfield  (Ludlow  Reservoir), 
the  first  summer  after  the  reservoir  was  filled  there  was  a  most 
distinct  odor  of  green  corn,  perceptible  for  a  quarter  of  a  mile 
from  the  pond  on  the  leeward  side.  The  pond  was  covered  with 
a  slime  of  algae,  partially  decayed ;  and  the  same  marked  odor 
was  noticed  at  the  water  troughs  along  the  line  of  the  aqueduct. 


TEMPERATURE   OF   SURFACE  WATERS.  9! 

When,  under  the  excessive  heat  of  summer,  the  algae  are  col- 
lected in  masses  and  begin  to  decay,  a  most  abominable  pig-pen 
or  horse-pond  odor  is  sometimes  noticed  in  the  ponds  ;  but  this  is 
seldom  noticed  in  the  water  drawn  from  the  service  pipes,  al- 
though a  foul  odor  similar  to  that  common  in  "  dead-ends"  does 
occur  when  water  containing  the  algae  stagnates  in  the  pipes. 

Besides  the  tastes  and  odors  which  may  with  reasonable  cer- 
tainty be  ascribed  to  the  growth  or  decay  of  organized  beings, 
there  have  been  certain  conditions  of  the  water  in  the  case  of 
many  water  supplies  which  are  very  enigmatical,  and  for  which 
no  satisfactory  explanation  has  been  offered.  The  so-called 
"  cucumber  "  taste,  and  the  other  tastes  characterized  as  "  fishy  " 
or  "  oily,"  occur  when  the  water  is  of  its  ordinary  purity  and  in 
waters  naturally  pure.  Some  have  maintained  that  the  tastes 
ought  to  be  due  to  the  presence  or  to  some  peculiar  condition  of 
the  algae,  but  as  it  is  impossible  to  discover  any  unusual  amount 
or  condition  of  those  algae,  which  are,  so  far  as  we  know,  harm- 
less, and  which  are  always  present,  and  as  none  of  those  algae 
which  are  known  to  produce  bad  tastes  and  odors  are  found,  it  is 
rather  difficult  to  accept  this  explanation.  Since  Professor  Rem- 
sen  has  found  reason  to  believe  that  the  recent  condition  of  the 
water  in  Farm  Pond  is  due  in  part,  at  any  rate,  to  the  decay  of 
a  sponge,  it  has  been  suggested  that  we  have  here  the  cause  of 
the  various  difficulties  heretofore  unexplained.  While  it  seems 
to  be  undoubtedly  true  that  the  sponge  may,  under  certain  cir- 
cumstances, produce  what  is  properly  spoken  of  as  a  "  cucumber  " 
taste,  there  are  many  cases  on  record  where  it  is  difficult  to  believe 
that  this  can  be  the  cause ;  and  with  reference  to  such  cases,  for 
the  present,  we  can  only  say,  "  We  do  not  know." 

Temperature  of  Surface   Waters. 

One  of  the  great  disadvantages  to  which  surface  water  is 
subject  is  the  variation  in  temperature.  The  water  in  winter  is 
but  a  few  degrees  above  the  freezing  point,  and  in  summer  the 
temperature  is  so  high  that  the  water  is  not  agreeable  as  a  bever- 
age unless  artificially  cooled.  The  use  of  ice  is  so  general  in  the 
United  States  that  much  less  stress  is  laid  upon  this  point  than 
in  other  countries,  but,  of  course,  a  considerable  proportion  of  the 
inhabitants  in  the  thickly  settled  parts  of  our  cities  are  unable  to 


92  WATER   SUPPLY. 

supply  themselves  regularly  with  ice.  Of  late  years  iced  water 
has  been  supplied  at  several  public  fountains  in  New  York,  and 
perhaps  in  other  cities.  It  would  be  difficult  to  isolate  the  effect 
of  the  temperature  of  the  water  on  the  public  health  from  the 
general  effect  of  the  hot  weather,  of  eating  unripe  and  decayed 
fruit,  and  of  other  causes,  all  of  which  affect  particularly  the 
poorer  class  of  the  population.  In  England,  the  increased  death- 
rate  of  the  warmer  months  has  been  connected  directly  with  the 
temperature  of  the  water  supply.  Thus,  in  the  report  of  the 
Registrar  General  for  July  22,  1878,  we  find: 

"  The  high  mortality  of  the  week  is  due  to  diarrhoea,  which 
becomes  fatal  in  London  when  the  temperature  of  the  Thames 
rises  above  60°  F.  Thus  the  Thames  temperature,  which  had 
been  60°,  rose  in  the  last  week  of  June  to  65°;  in  the  following 
weeks  it  was  68°,  66°,  67°  F.  The  weekly  deaths  from  diarrhoea 
and  simple  cholera,  which  had  been  23,  rose  to  78,  156,  256,  349 
in  corresponding  weeks."  To  show  that  this  increase  was  not 
due  simply  to  the  increased  atmospheric  temperature  and  its 
attendant  discomforts,  it  is  stated  that  "  the  deaths  from  diar- 
rhoea are  differently  distributed  in  the  fields  of  the  water  com- 
panies ;  thus  the  deaths  in  the  last  four  weeks  were  786  in  the 
districts  supplied  by  the  Thames  and  Lea  waters,  whereas  the 
deaths  in  the  districts  supplied  with  water  drawn  from  the  chalk 
by  the  Kent  company  were  19;  out  of  the  same  population,  the 
deaths  in  the  former  were  to  the  deaths  in  the  latter  as  3  to  I." 
The  temperature  of  the  Kent  company's  water  at  the  wells  was 
uniformly  52°  F.;  at  the  same  time  it  must  be  noted  that  the 
waters  differed  not  simply  with  respect  to  temperature.  The 
water  of  the  Kent  company  is  harder,  and,  what  is  perhaps  more 
important,  it  contains  but  little  organic  matter. 

Baldwin  Latham,  while  believing  that  "  the  summer  diarrhoea 
is  governed  by  the  influence  of  the  temperature  of  our  water 
supply,  as  invariably  the  disease  becomes  epidemic  when  the 
water,  whatever  be  its  source  of  supply,  reaches  a  temperature 
of  62°  F.  (16°. 7  C.),"  attempts  to  show  that  the  temperature  of 
the  water  delivered  to  the  consumers  is  much  less  dependent 
upon  the  original  temperature  at  the  source  than  is  usually  sup- 
posed, and  that  if  the  water  is  carried  for  any  considerable  dis- 
tance in  the  mains,  it  approaches  or  acquires  the  temperature  of 
the  ground  in  which  the  pipes  are  laid,  as  appears  from  the 


TEMPERATURE   OF   SURFACE   WATERS. 


93 


following  table.*  Here  the  Kent  water,  alluded  to  as  having  a 
uniform  temperature  at  its  source,  appears,  when  delivered,  as 
variable  as  the  water  of  the  Thames.  He  asserts  f  that  the 
general  mortality  in  London  from  diarrhoea  is  practically  the 
same  in  the  districts  supplied  from  the  rivers  as  in  those  supplied 
by  the  Kent  Water  Company,  but  that  the  water  in  the  latter 
region  does  not  reach  its  highest  temperature  until  later  in  the 
season,  owing  to  the  advantage  which  the  lower  initial  tempera- 

TABLE  X. — TEMPERATURE  OF  LONDON  WATER  SUPPLIES. 
[The  degrees  are  Centigrade.] 


DATE. 

KENT  COMPANY'S  WATER. 
In  the  wells.  I  In  the  mains. 

THAMES 
WATER  IN 
THE  MAINS. 

THE  GROUND 

OF   MI 

0.838. 

AT  A  DEPTH 
:TERS 

1.448. 

Tulv            1878 

10.59 
10.67 
10.71 
10.68 
10.  61 
10.50 

10.45 
10.40 

10.35 
10.44 
10.42 
10.57 

1  6.  80 
16.62 
14.78 
12.90 
8.17 
5.98 
5.06 

5-45 
6.30 
8.38 
9-36 
12.63 

18.39 
17.70 
14.92 
12.87 
7-47 
5.14 
4-77 
5-72 
7.20 
8.20 
IO.2O 
14.25 

17.66 
17.16 

15.28 

12.53 
6.98 
3-72 
2.80 
3-58 
4-97 
6.80 

7.32 
13.01 

15.47 
16.05 
15.04 
13.05    • 
9.04 

6.12 

4.68 
4.66 

5.54 

6.85 

8.31 

11.23 

August               

October 

November 

December          

January,     1870.  . 

February,           
March                   .    ... 

April                   

May 

June 

ture  gives  to  it.  It  will  be  understood  that  Latham's  figures  have 
reference  to  the  temperature  acquired  in  the  service  pipes;  J  the 
water  passing  through  the  main  conduit  or  even  through  the 
large  iron  mains  suffers  much  less  change  of  temperature  than 
Table  X  would  indicate.§  Latham  has  patented  an  apparatus 
for  "  tempering  "  the  water,  which  consists  "  of  a  vertical  tube 
driven  or  screwed  into  the  ground  to  a  depth  of  about  25  feet,  the 
water  being  admitted  at  the  top  and  withdrawn  at  the  bottom, 
and  special  arrangements  being  adopted  for  the  protection  of  the 
ascending  pipe."  With  such  an  apparatus  interposed  in  the 
service  connection  of  the  house,  "  the  range  of  temperature  in 

*  Quoted  from  Journal  fur  Gasbeleuchtung  und  Wasserversorgung,  xxii  (1879), 
p.  756. 

f  Journal  of  Society  of  Arts,  Sept.  17,  1880. 

\  The  temperatures  given  in  the  reports  of  Dr.  Frankland  to  the  Registrar  Gen- 
eral were  taken  in  the  company's  mains  at  Deptford,  near  the  source  of  the  water. 

§  This  matter  is  discussed  at  length  and  mathematically  by  Perissini :  Journ.  fur 
Gasb.  und  Wasserv.,  xxiii  (1880),  pp.  608  and  644. 


94 


WATER   SUPPLY. 


the  water  required  for  dietetic  purposes  need  not  exceed  3°  F. 
throughout  the  year,  when  drawn  from  a  3-inch  tube  at  a  rate 
not  exceeding  one  gallon  every  half-hour." 

The  question  of  temperature  is  an  important  one  in  bodies  of 
stored  water,  as  the  troublesome  algae  already  alluded  to  seem  to 
require  a  somewhat  elevated  temperature  (approaching  70°  F.) 
for  their  rapid  and  abundant  development ;  when  collected  as  a 
scum  they  are  killed  and  enter  into  decay  when  the  water  be- 
comes strongly  heated  in  midsummer.  While  it  is,  of  course, 
impracticable  to  cover  ponds  and  impounding  reservoirs,  it  is  of 
advantage  to  cover  the  smaller  storage  reservoirs  which  are  fre- 
quently used  in  connection  with  water-works  to  contain  a  reserve 
supply,  or  a  supply  for  a  limited  number  of  days,  and  thus  to  pre- 
vent, to  a  certain  extent,  the  elevation  of  temperature  to  which 

TABLE  XI. — OBSERVATIONS  OF  TEMPERATURE  IN  FRESH  POND,  MASS.* 


DATE. 

TEMPERATUR 

2 

II 
o  h 

ii 

H 

E  (EXPRESSED  IN 
DEGREES)  AT 

|| 

=  2 

*l 

II 
9 

CENTIGRADE 

||  j 

ni 

<n      « 

^e 
|ll 

May 
June 

Juy 

August 

<« 

November 
December 

January 
it 

April 
May 

A     lS78..  . 

i6°.5 

14-5 
19. 

17-3 
20.5 

22.2 
28.0 
26.0 

25-3 
24.0 
24.0 
24.0 
24.0 
22-3 

9-5 
4-5 
0-5 
0.7 

°-9 
6.0 

18.5 

0 

12.5 
14-5 

16.5 

16.8 
16.8 
16.6 
16.7 

iS-4 
16.8 
16.8 
17-3 

20.1 
20.  0 
2O.  O 
9.2 

4-3 

I.O 

i-3 

2.0 

5-o 
13-0 

0 

8.5 

8-5 
8.8 
8.6 

8-7 
9.2 

9-3 
9.2 
9.6 
9-9 

10.  1 
10.  0 
10.2 
10.  0 
8.7 

4-5 

I.O 

i-7 

1.8 

4-4 

8.3 

16                    

6  

27 

7" 

2     l87Q 

22                                ..... 

*  First  Annual  Report  of  Mass.  State  Board  of  Health,  Lunacy  and  Charity,  1880. 
Supplement,  p.  98. 


TEMPERATURE   OF   SURFACE   WATERS.  95 

a  small  and  comparatively  shallow  body  of  water  is  subject  under 
a  summer's  sun.  ,  -.  , 

Table  XI  shows  the  variation  in  temperature  of  the  surface 
water  in  a  pond  near  Boston,  Mass.  (lat.  about  42°),  which  is  used 
as  a  source  of  city  supply ;  and  also  the  variation  at  different 
depths. 

For  making  observations  on  the  temperatures  of  bodies  of 
water,  especially  below  the  surface,  thermometer  makers  supply- 
instruments  surrounded  by  a  copper  tube  in  which  some  of 
the  water  is  brought  to  the  surface.  Where  samples  for  an- 
alysis are  taken  at  the  same  time,  a  chemical  thermometer 
may  be  inserted  in  the  bottle  used  for  the  collection  of  the 
water.  The  bottle  having  been  sunk  to  the  required  depth,  the 
stopper  is  withdrawn,  and  after  the  bottle  has  filled  it  is  allowed 
to  remain  until  it  is  certain  that  the  whole  apparatus  has  acquired 
the  actual  temperature  of  the  water.  It  is  then  drawn  up  and 
the  reading  of  the  thermometer  is  taken  quickly  while  still  sur- 
rounded by  water.  This  method  answers  very  well,  with  care,  up 
to  depths  of  80  feet. 

A  very  convenient  instrument  for  taking  temperature  at  va- 
rious depths  is  the  "  New  Standard  Deep  Sea  Thermometer," 
made  by  Negretti  and  Zambra,  London.  The  construction  of 
the  thermometer  is  shown  in  Fig.  15,  c.  To  protect  it  against 
pressure,  this  thermometer  is  inclosed  in  a  glass  tube,  hermet- 
ically sealed,  the  portion  which  surrounds  the  thermometer 
bulb  being  filled  with  mercury.  The  object  of  the  mercury  is  to 
furnish  a  good  conductor  of  heat  between  the  outer  wall  and  the 
thermometer  bulb,  and  it  is  confined  in  place  by  a  partition  ce- 
mented on  to  the  neck  of  the  bulb.  The  whole  apparatus  is 
inserted  into  a  hollow  wooden  frame  containing  a  quantity  of 
lead  shot.  When  the  thermometer  is  lowered  to  any  depth,  it 
descends  as  shown  in  Fig.  15,  a,  and  the  bulb  of  the  thermome- 
ter is  downward ;  it  is  allowed  to  remain  at  the  required  depth 
for  a  few  minutes  in  order  that  the  thermometer  may  acquire  the 
temperature  of  the  place,  the  mercury  rising  or  falling  in  the 
capillary  tube  as  in  an  ordinary  thermometer.  Finally,  a  sudden 
pull  is  made  on  the  line,  and  the  instrument,  owing  to  the  resist- 
ance of  the  water  and  the  consequent  displacement  of  the  center 
of  gravity  (the  shot  falling  to  the  other  end  of  the  frame),  will 
turn  over  and  be  drawn  upward  with  the  thermometer  in  the 


96 


WATER  SUPPLY. 


position  shown  in  Fig.  15,  b.  When  the  thermometer  is  inverted, 
the  mercury  column  breaks  at  the  constriction  A,  and  falls  to  the 
other  end  of  the  tube,  from  which  the  degrees  are  read  off,  as 
shown  in  the  figure,  with  the  bulb  of  the  thermometer  upper- 
most. 

As  with  any  thermometer,  it  is  necessary  to  determine  the 


DESCENDING. 


ASCENDING. 


FIG.  15,  a. 


FIG.  15,  c. 


FIG.  15,  b. 


error  of  graduation  once  for  all,  and  the  error  of  the  zero 
point  from  time  to  time.  For  very  nice  work,  a  correction 
should  also  be  made  for  the  temperature  of  the  mercury  column 
at  the  time  of  reading,  but  in  ordinary  work  this  is  not  neces- 
sary. 

Examination  of  Surf  ace  Waters. 
In  choosing  a  surface  water  as  a  source  of  supply,  there  are 


EXAMINATION   OF   SURFACE  WATERS.  97 

certain  concessions  which  must  be  made.  In  the  first  place,  the 
water  will  be,  almost  inevitably,  somewhat  colored,  especially  if 
taken  from  a  pond  or  lake  ;  in  the  second  place,  there  will  usually 
be  a  slight  "  pondy  "  taste,  even  in  the  best  of  surface  waters. 
Considered  simply  as  drinking  water,  surface  water  will  always 
be  at  a  disadvantage  by  the  side  of  a  pure,  soft  spring  water,  but, 
as  stated  on  previous  pages,  a  surface  water  may  often  be,  on  the 
whole,  the  best  suited  for  a  general  supply. 

In  examining  as  to  the  suitability  of  any  source  of  surface 
water,  after  determining  whether  a  sufficient  amount  can  be  ob- 
tained directly  or  by  means  of  storage  reservoirs,  the  desirability 
of  the  source  can  be  ascertained  better  by  a  survey  of  the  drain- 
age area,  and  by  a  knowledge  of  the  present  population  and 
sources  of  pollution,  and  the  probable  increase  in  the  future,  than 
from  the  results  of  chemical  examination  of  the  water,  the  inter- 
pretation of  which  is  sometimes  attended  with  difficulty.  It 
may  be  possible,  it  is  true,  to  state  from  the  chemical  examina- 
tion of  a  single  sample  that  no  considerable  or  no  appreciable 
contamination  exists  ;  it  is  impossible  to  recommend  a  water  for 
drinking  without  knowing  something  of  the  situation  and  sur- 
roundings of  the  source  from  which  it  is  taken. 

The  principal  difficulties  in  the  way  of  the  satisfactory  chemi- 
cal examination  of  surface  waters  are  three  in  number:  In  the 
first  place,  the  volume  of  water  is  generally  so  large  that,  even 
when  polluting  matter  is  known  to  be  present,  the  dilution  is  so 
great  as  to  prevent  the  detection  of  unmistakable  evidence  of 
contamination.  In  the  second  place,  all  surface  waters  contain 
more  or  less  of  organic  substances — substances  containing  carbon 
and  nitrogen — which  it  is  impossible  to  refer  definitely  to  animal 
or  vegetable  sources,  or  otherwise  to  distinguish  as  harmless  and 
harmful.  In  the  third  place,  the  water  of  such  streams  and 
ponds  is  subject  to  very  considerable  variation,  so  that  the  ex- 
amination of  a  single  sample  is  of  comparatively  little  value. 
With  reference  to  the  second  point  something  has  already  been 
said  in  the  chapter  on  water  analysis.  It  may  be  said  further 
that  the  substances  which  form  the  most  offensive  part  of  the 
soluble  vegetable  matter  are  albuminous  in  character,  and  the 
chemical  effect  on  the  water  is  to  increase  the  amount  of  what 
is  designated  as  "  albuminoid  ammonia ; "  that  is,  they  contain 
nitrogen,  which,  under  the  analytical  treatment,  is  evolved  and 
7 


98  WATER   SUPPLY. 

measured  as  ammonia.  It  is  unfortunately  impossible  by  ana- 
lytical means  to  distinguish  whether  this  "albuminoid  ammonia" 
is  to  be  ascribed,  in  any  given  case,  to  vegetable  or  to  animal 
origin.  No  doubt  the  excrement  of  fishes,  their  dead  bodies  so 
far  as  they  are  not  consumed  by  their  living  comrades  and  by 
the  animalcules,  and  the  bodies  of  the  animalcules  themselves 
add  to  the  nitrogenous  organic  matter  in  our  surface  waters.  As 
a  rule,  in  waters  not  contaminated  by  sewage,  the  animal  matter 
forms  only  a  trifling  proportion  of  the  entire  organic  matter,  but 
the  recent  investigation  of  Professor  Remsen  shows  that  in  some 
instances  the  animal  matter  (as  from  sponges)  may  be  apprecia- 
ble and  of  practical  importance. 

In  the  case  of  a  bad  condition  of  the  water  arising  from  the 
decay  of  an  unusual  amount  of  animal  or  vegetable  matter  on 
the  bottom  or  sides  of  a  reservoir,  or  from  the  presence  of  algae, 
the  water  is  ordinarily  characterized  by  an  abnormal  amount  of 
soluble  organic  matter,  which  shows  itself  in  the  common  method 
of  analysis  as  <4  albuminoid  ammonia,"  or  in  the  Frankland 
method  as  "  organic  carbon  "  and  "  organic  nitrogen."  But,  in 
order  to  judge  whether  the  amount  is  abnormal  or  not,  it  is  nec- 
essary to  have  an  extended  series  of  analyses,  and  this  is  seldom 
at  hand.  The  effect  of  algae  may  be  well  seen  by  a  study  of  the 
weekly  analyses  of  the  Springfield  water  for  the  years  1876  and 
1877,  and  of  the  Mystic  during  1879,  as  shown  in  the  respective 
water  reports.* 

As,  in  this  country,  waters  have  been  and  are  most  frequently 
examined  by  the  "  ammonia "  process,  attempts  have  been 
made  to  fix  the  limit  of  "  albuminoid  ammonia"  which  may  be 
allowed  in  a  surface  water.  Wanklyn,  as  stated  on  page  41, 
looks  upon  o.oio  part  of  "albuminoid  ammonia"  in  100,000  as 
suspicious,  and  upon  0.015  part  as  sufficient  to  condemn  a  water, 
and  some  analysts  are  inclined  to  adopt  this  standard  for  our  sur- 
face waters ;  such  an  absolute  standard  is,  however,  impractica- 
ble, and  would  exclude  many  waters  which  are  known  to  be  free 
from  contamination  arid  to  be  perfectly  well  suited  for  domestic 
use.  With  reference  to  this  matter  Dr.  Smart  says :  f 

*  See  Annual  Reports  of  the  Water  Commissioners  of  the  City  of  Springfield 
(Mass.),  1877  and  1878.  Also,  First  Annual  Report  of  Massachusetts  State  Board  of 
Health,  Lunacy  and  Charity.  Supp.,  pages  119,  120. 

\  Buck's  Hygiene,  ii,  p.  128. 


EXAMINATION  OF   SURFACE  WATERS.  99 

"The  waters  of  the  purest  mountain  streams  in  our  unsettled 
West,  where  animal  contamination  is  an  impossibility,  contain 
0.014  part  per  100,000  of  albuminoid  ammonia.  At  other  times 
they  may  yield  0.020,  0.025  or  more,  and  yet  be  regarded  as  com- 
paratively innocent." 

Dr.  Smart  found  the  Black's  Fork,  Wyoming,  to  contain  0.014 
part  in  100,000  when  most  free  from  surface  admixture,  and 
0.028  part  when  swollen  by  melting  snows.  The  Little  Wind 
River,  Wyoming,  a  stream  running  over  a  rocky  bed  and  contain- 
ing only  about  3.75  parts  of  total  solids  in  100,000,  gave  0.034 
part  of  "  albuminoid  ammonia."  The  North  Platte  River  yields 
from  0.030  to  0.050  part  in  100,000  at  different  times.  The  ques- 
tion may  be  pertinently  asked  how  it  is  that  our  surface  waters 
contain  so  much  more  organic  matter  than  the  waters  of  Great 
Britain  ?  Dr.  Smart  says  :  "  These  streams  ought  to  be  pure,  if 
pure  water  is  to  be  found  in  nature,  as  they  run  through  no  pop- 
ulous districts  and  are  thus  free  from  the  sources  of  contamina- 
tion against  which  sanitary  officers  are  most  on  guard.  They 
spring  from  a  cleft  in  the  rocks,  are  mostly  rapid  in  their  course 
until  they  reach  the  plains,  and  are  fed  by  the  rainfalls  and  melt- 
ing snows.  There  seems  nothing  left  by  way  of  explanation 
but  the  wildness  of  the  country  through  which  they  run.  In 
England  the  fields  are  fenced  in  and  the  soil  cultivated  to  the 
very  banks  of  the  stream,  the  woods  are  well  kept,  and  the 
swamps  are  drained  and  reclaimed ;  but  here  there  is  no  cultiva- 
tion ;  vegetation  lives,  and,  instead  of  being  garnered  up,  dies 
and  decays.  The  forest  trees  fall  and  rot  where  they  fall.  I 
have  been  up  in  the  Uintah  Mountains,  where  are  the  sources  of 
the  Black's  Fork,  and  among  the  pines  covering  the  slopes  of 
the  ridge  there  are  more  fallen  trees  in  all  stages  of  decay  than 
living  ones  in  those  untouched  forests.  Through  such  dead 
vegetation  the  streams  have  to  force  their  way,  and  it  would  be 
singular  indeed  if  they  did  not  take  up  a  portion  of  the  soluble 
organic  matter.  But,  in  addition,  in  the  tangled  willow  growths 
of  the  valleys,  where,  as  in  the  forests,  the  growth  of  to-day  rises 
from  the  decay  of  ages,  the  beaver  dams  up  the  stream,  and 
vast  masses  of  water  are  stagnated,  to  dissolve  the  dead  vegeta- 
ble tissues  and  find  their  way  by  slow  degrees  back  into  the  beds 
of  the  running  water." 

"  That  the  dissolved  organic  matter  is  vegetable  in  its  origin, 


100  WATER  SUPPLY. 

is  also  shown  by  the  absence  of  chlorides  and  nitrites,  and  that 
it  is  recent,  by  the  frequent  absence  of  ammonia." 

It  must  not  be  understood  that  the  presence  of  an  excess  of 
vegetable  matter  is  absolutely  a  matter  of  indifference.  Waters 
thus  charged  may  be  the  cause  of  diseases  of  the  digestive  or- 
gans, without  doubt.  Whether  they  may  also  cause  any  of  the 
so-called  zymotic  diseases  or  give  rise  to  specific  diseases  of  pe- 
culiar type,  is  doubtful. 

Dr.  Smart,  whose  opinion  is  entitled  to  much  weight,  ascribes 
the  "  mountain  fever  "  of  the  West  to  this  cause  (compare  page 
52).  He  says: 

"  As  animal  matter,  in  certain  stages  of  its  decomposition,  or 
enveloping  specific  germs,  gives  expression  to  its  presence  in  the 
system  by  the  development  of  typhoid  fever,  so  vegetable  mat- 
ter, in  certain  stages  of  its  decomposition,  or  enveloping  specific 
germs,  gives  rise  to  an  adynamic  remittent,  for  which  the  writer 
has  suggested  the  name  of  aquamalarial  fever.  Viewed  in  its 
connection  with  this  affection,  the  organic  ammonia  should  not 
exceed  0.016  part  in  100,000,  for  when  0.020  is  reached,  the  disease 
makes  its  appearance,  and  becomes  more  pernicious  in  individual 
cases  as  the  amount  increases.  Not  that  aquamalarial  develop- 
ments are  to  be  expected  in  every  case  where  the  organic  ammo- 
nia exceeds  this  limit,  but  that  experience  shows  a  greater  prob- 
ability of  their  occurrence  with  a  water  thus  impregnated — ma- 
laria being  more  likely  to  be  present  with  a  large  than  a  small 
vegetable  contamination." 

With  reference  to  the  third  point  alluded  to  above  as  afford- 
ing difficulty  in  the  interpretation  of  the  results  of  chemical  ex- 
amination, it  may  be  said  that  the  results  of  a  single  examination 
are  to  be  received  with  a  good  deal  of  caution,  and  such  results 
must  be  interpreted  somewhat  according  to  the  season  of  the 
year  in  which  the  sample  is  taken.  The  very  considerable  varia- 
tion to  which  streams  are  subject,  as  far  as  the  suspended  matter 
is  concerned,  has  been  shown  in  Table  VII,  on  page  57.  The 
state  of  things  is  similar  with  reference  to  the  matter  in  solution, 
especially  with  streams  in  which  the  volume  of  water  is  subject 
to  much  variation.  Thus  the  Hooghly,  at  Calcutta,  is  stated 
to  carry : 

21.68  parts  in  100,000 of  "total  solids"  in  May, 
11.30    "      "        "      "       "        "        "  October. 


EXAMINATION  OF  SURFACE  WATERS. 


IOI 


The  rainy  season  greatly  increases  its  purity,  and  the  melting 
of  the  snow  on  the  Himalayan  Range  helps  in  the  same  direction, 
so  that  the  water  is  most  pure  in  October.*  Further  illustration 
of  the  variation  to  which  surface  waters  are  subject,  particularly 
with  regard  to  the  organic  matter,  may  be  seen  from  the  follow- 
ing tables.  Table  XII  shows  the  variation  in  the  sum  of  the 
"  organic  carbon"  and  "  organic  nitrogen,"  and  also  in  the  "  albu- 
minoid ammonia,"  as  observed  in  the  case  of  the  Mystic  water, 
which  is  supplied  to  a  portion  of  Boston,  Mass. 

TABLE  XII.— EXAMINATION  OF  MYSTIC  WATER. 

[Results  expressed  in  Parts  in  100,000.] 


DATE. 

No.  OF  SAMPLES. 

SUM  OF  THE 

ORGANIC 

ELEMENTS. 

"  ALBUMINOID 
AMMONIA." 

Ave 

rage  c 

f    2  sam 
4 
4 
3 

5 

2 

I 
2 

3 
4 
4 

12 

pies 

0.478 

0-775 
0.605 
0.448 
0-333 
0-393 
0.297 

0.364 
0.486 

0.852 
0.526 
0-375 

0.035 
O.O26 
0.020 

o  014 

O.OII 
O.OII 
0.012 

0.034 
O.O22 
0.014 

Tulv 

August                   

October 

November                 

December     

Tune  IQ  to  July  3 

July  10  to  Aug    7  

Aii£j    14  to  Sept    ii 

Sept    i  8  to  Fan    15 

In  this  case,  the  large  variation  was  partly  due  to  the  pres- 
ence of  an  abundant  growth  of  algae,  the  trouble  being  at  its 
height  in  the  latter  part  of  July  and  during  August.  But,  in  the 
absence  of  any  such  growth,  the  variation  is  often  very  great. 
Weekly  examinations  of  the  Cochituate  supply  of  the  city  of 
Boston  from  July,  1876,  to  July,  1877,  showed  a  variation 

in  the  ammonia from  0.0005  to  0.0056  part  in  100,000 

in  the  "  albuminoid  ammonia  " from  0.0099  to  0.0176     "     "         " 

in  the  total  solids.    from  3. 72      105.58         "     "         " 

Further  illustration  of  this  point  is  afforded  by  Tables  XIII 
and  XIV. 

Table  XIII  contains  the  results  of  monthly  examinations  of 
the  water  of  Glasgow,  Scotland,  as  reported  by  Professor  Gustav 
Bischof  of  the  Andersonian  University.  The  water  comes  from 

*Proc,  Inst.  Civ.  Eng,  Gr.  Br.,  Ixiv,  p.  361. 


102 


WATER   SUPPLY. 


TABLE  XIII.  —EXAMINATION  OF  GLASGOW  WATER  BY  PROFESSOR  BISCHOF. 

[Results  expressed  in  Parts  in  100,000.] 


DATE. 

ORGANIC 
CARBON. 

ORGANIC 

NITROGEN. 

SUM  OF  OR- 
GANIC ELE- 
MENTS. 

O  204 

O  OI7 

O   221 

o  181 

o  016 

O    IQ7 

July      18, 

o  008 

O    2OQ 

o  on 

O   22O 

Sept.       i,           

o  156 

O   O47 

o  203 

Oct.      14 

O2C6 

o  028 

o  284 

OI77 

OQOC 

O    212 

Jan.       15,  1874  

O    I  ^4 

O   O2  1 

O    1  7^ 

Feb        < 

O2CI 

o  008 

o  185 

O   OO7 

O    IQ2 

April      i,           

O    1  60 

o  003 

O    172 

Mav        $ 

Oooe 

O  Oil 

o  246 

O   JO7 

o  018 

0.21^ 

an  unpolluted  Highland  lake,  Loch  Katrine,  and  flows  some 
thirty-six  miles  in  a  masonry  conduit.  Table  XIV,  which,  like 
No.  XIII,  is  compiled  from  the  Sixth  Report  of  the  Rivers  Pol- 
lution Commission,  shows  the  variation  in  the  water  of  the  sev- 
eral companies  which  supply  London  with  filtered  river  water. 
These  are  not  monthly  averages,  but  the  results  of  the  examina- 
tion of  single  samples  taken  at  monthly  intervals. 

TABLE  XIV. — VARIATION  IN  MONTHLY  SAMPLES  OF  LONDON  WATER,  1873. 


NAME  OF  COMPANT. 

ORC 

Maximum 
at  any  one 
time. 

;ANIC  CARB 

Minimum 
at  any  one 
time. 

ON. 

Mean 
of  12 
Samples. 

ORGANIC  NITRO 

Maximum  Minimum 
at  any  one  at  any  one 
time.           time. 

GEN. 

Mean 

Of  12 

Samples. 

Chelsea  

0.447 
0.341 
0.396 
0.412 
0.449 
0.257 
0-333 

O.I2I 
O.II4 
O.II8 
O.II7 
0.130 
0.059 
0.109 

0.197 
0.173 
0.186 
0.183 
O.2O6 
0.107 
0.175 

0.067 
0.055 
0.060 
0.050 
0.065 
0.032 
O.O82 

0.013 
0.015 
0.020 

0.016 

0.021 
O.OIO 

0.015 

0.034 
0.028 
0.030 
0.032 
0.040 
O.OlS 
0-035 

West  Middlesex 

Southwark 

Grand  Junction     

Lambeth  

New  River               . 

East  London   

It  may  be  said,  in  general,  that  no  source  of  surface  supply 
should  be  adopted  on  the  strength  of  examinations  made  in  the 
winter  season,  and  in  the  case  of  ponds  and  lakes  the  examina- 
tion should  include  a  careful  survey  of  the  shallow  portions 
during  the  hot  weather,  with  a  view  of  discovering  the  possible 
presence  of  noxious  algae.  Negative  results  in  this  direction  will 
not,  however,  guarantee  future  immunity. 


EXAMINATION   OF   SURFACE  WATERS. 


103 


As  already  intimated,  the  preliminary  examination  of  a  sur- 
face water,  from  a  sanitary  point  of  view,  concerns  itself  chiefly 
with  the  present  and  probable  future  pollution,  and  this  must  be 
considered  with  reference  to  the  volume  of  water  with  which  the 
polluting  substances  will  be  diluted,  taking  care  to  err  rather  on 
the  side  of  safety :  the  chemical  examination  should  not,  how- 
ever, be  omitted,  as  the  results,  if  properly  interpreted,  may  be 
of  great  value.  Tables  XV  and  XVI  will  furnish  data  for  com- 
parison in  the  case  of  surface  waters. 

TABLE  XV.— EXAMINATION  OF  SURFACE  WATERS. 
[Results  expressed  in  Parts  in  ioo,oco.] 


Z 

.i  I 

Z 

H 

HARDNESS, 

| 

0 

O 

S 

ia 

8 

GEOLOGICAL  FOR- 
MATION. 

SOLIDS. 

a 

u 

ic  NITR 

, 

</i  3 

<  z 

ht 

3OMB1N1 
EN. 

sP 

M 

1 

I 

B 

% 

C/3 

1 

1 

1 

z 
o 

s 

* 

p< 
gee 

i 

i«3 

I 

a; 

1 

!' 

3 

tu 
O 

d 

H 

O 

O 

* 

H 

P-. 

U 

H 

£ 

H 

fc 

Igneous  rocks  • 
Metamorphic,  Cam- 

5-5 

0.278 

0.033 

0.001 

0.002 

0.035 

0 

I.»3 

O.I 

2.O 

2.1 

18 

brian,    Silu  r  i  a  n, 

and  Devonian.... 
Yoredale  and  Mill- 

5.12 

0.293 

0.024 

0.002 

0.006 

0.031 

3 

0.92 

0.3 

2-5 

2.8 

81 

stone     Grit,    and 

non-calc  a  r  e  o  u  s 

Coal-measures  .  .  . 
Calcareous    portion 

8-75 

0-377 

0.033 

0.003 

0.010 

0.050 

6 

1.05 

0.4 

4-3 

4-7 

47 

of  Coal-measures. 

22.79 

0.346 

0.033 

0.007 

0.016 

0.056 

33 

1.52 

4.0 

8-3 

12.3 

26 

SURFACE  WATERS 

FROM  CULTIVATED 

LAND. 

Non-calcareous  dis- 

tricts   
Calcareo  us     d  i  s  - 

9.52 

0.276 

0.034 

0.007 

0.089 

0.128 

635 

i.49 

0.6 

4-3 

4.9 

3i 

tricts  

30.08 

0.268 

0.053 

0.005 

0.257 

0.314 

2,306 

2.24 

12.4 

8.2 

20.6 

12 

In  Table  XV  are  presented  the  results  obtained  by  the  Rivers 
Pollution  Commission  from  the  examination  of  a  large  number 
of  samples  of  surface  water  from  various  geological  regions,  the 
organic  matter  being  indicated  by  the  determination  of  the  "  or- 
ganic carbon "  and  "  organic  nitrogen."  In  Table  XVI  are 
brought  together  the  results  of  the  examination  of  various  Amer- 
ican surface  waters,  mostly  in  actual  use  as  sources  of  supply, 
the  organic  matter  being  indicated  by  the  "  albuminoid  ammo- 
nia." 


*  Sixth  Report  of  Rivers  Pollution  Commission. 


104 


WATER  SUPPLY. 


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LOCALITY. 

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!""£-  liivl  B    aJlll^l1 

CHAPTER  VI. 

GROUND  WATER  AS  A  SOURCE  OF  SUPPLY. 

A  PORTION  of  the  water  which  falls  as  rain  or  snow  sinks  into 
the  earth,  and  where  the  surface  deposit  is  gravel  or  other 
porous  material  overlying  some  impervious  rock,  the  water  col- 
lects to  constitute  the  ground  water  of  the  locality,  the  water- 
table  of  the  engineer.  The  rivers  which  flow  through  such  a 
deposit,  or  the  ponds  and  lakes  which  are  situated  in  it,  deter- 
mine the  level  of  the  ground  water  in  their  banks;  but  as  we 
recede  from  the  banks  the  water  level  is  found  to  rise  more  or 
less  regularly,  according  to  the  character  of  the  porous  stratum. 
Although  subject  to  fluctuation,  the  ground  water  often  main- 
tains a  very  uniform  relative  level  over  large  areas :  its  height  and 
fluctuations  are  important  factors  in  the  sanitary  condition  of 
any  locality. 

The  cause  of  the  rise  of  the  ground  water  as  we  recede  from 
the  wells — a  fact  which  has  been  established  by  numerous  obser- 
vations in  this  country  and  in  Europe  * — is  evident :  the  water 
falling  upon  the  whole  water-bearing  area  would  naturally  raise 
the  level  of  the  ground  water ;  that  level  cannot  be  permanently 
higher  than  the  water  in  the  natural  drainage  channels  in  their 
immediate  neighborhood,  as  there  is  a  continual  passage  of  water 
through  the  porous  material  to  the  visible  streams  or  lakes. 
Owing  to  the  resistance  of  the  material  through  which  the  water 
passes,  the  surface  will  be  an  inclined  one,  and  the  amount  of 
inclination  will  depend  upon  the  resistance  encountered.  On 
Long  Island,  N.  Y.,  the  inclination  is  quite  uniform  from  the 

*  A  great  many  profiles  resulting  from  actual  measurements,  and  showing  the 
inclination  of  the  ground  water,  may  be  found  in  the  Berlin  and  Munich  reports,  the 
titles  of  which  appear  on  pages  217-218.  In  the  latter  the  profiles  include  the  sur- 
face levels,  the  level  of  the  ground  water,  and  the  level  of  the  underlying  impervious 
stratum,  and  are  very  instructive.  See  also,  The  Brooklyn  Water-Works  and  Sewers. 
New  York,  1867. 


IO6  WATER  SUPPLY. 

central  ridge  to  the  ocean  or  to  Long  Island  Sound,  and  averages 
about  seven  feet  to  the  mile.  In  the  valley  of  the  Sacramento 
the  general  slope  is  about  four  feet  in  a  mile.  In  some  localities 
the  inclination  is  much  greater  than  this  for  limited  distances ; 
thus,  in  the  neighborhood  of  the  Taunton  (Mass.),  Water  Works 
there  is  a  fall,  in  what  seems  to  be  a  continuous  water-table,  of 
about  14  feet  in  1,000.  Besides  the  slope  towards  a  visible 
stream,  there  is  often  a  fall  in  the  ground  water  in  the  direction 
of  the  mouth  of  the  stream,  and  a  corresponding  flow.  It  will 
be  understood,  however,  that  the  "  flow  "  has  reference  generally 
to  a  rather  slow  passage  through  the  interstices  of  the  ground : 
sometimes,  however,  on  account  of  a  lack  of  homogeneousness  in 
the  water-bearing  stratum,  veins  of  water  occur,  in  which  the 
flow  may  be  quite  rapid. 

The  water  obtained  by  sinking  a  well  into  a  stratum  of  sand 
or  gravel  which  has  not  been  artificially  disturbed,  is,  as  a  rule, 
bright  and  clear,  and  free,  or  nearly  free,  from  organic  matter. 
Although  originally  coming  from  the  atmosphere,  in  its  slow 
passage  into  and  through  the  ground,  the  water  has  been  sub- 
jected to  a  long  process  of  sedimentation  and  filtration,  com- 
bined with  processes  of  oxidation.  In  this  sense,  the  water  may 
be  said  to  have  been  purified  by  natural  filtration :  the  process, 
however,  is  not  brought  about  by  the  means  taken  to  collect  and 
utilize  the  water,  but  has  been  practically  completed  before  the 
demand  is  made  upon  it. 

Utilization  of  the  Ground  Water. 

The  most  simple  method  of  making  the  ground  water  availa- 
ble, and  the  one  earliest  adopted,  is  to  sink  a  well,  covered  or 
open,  into  the  water-bearing  stratum,  and  to  pump  therefrom. 
Such  a  well,  which  draws  its  supply  from  the  ground  water  proper, 
is  generally  called  a  shallow  well,  in  distinction  from  a  deep  well, 
which  may  extend  into  a  rocky  stratum,  and  obtain  its  supply  from 
a  water-bearing  fissure ;  and  in  distinction  also  from  an  artesian 
well  sunk  to  a  considerable  depth  into  underlying  strata  which 
have  no  connection  with  the  ground  water  of  the  particular 
locality.  This  method  of  obtaining  water  from  shallow  wells  has 
been  practised  from  time  immemorial  for  the  supply  of  single 
families  and  small  communities,  and  is,  nowadays,  used  on  a  large 
scale  for  furnishing  town  supplies.  In  many  places  the  well,  from 


GROUND   WATER  AS  A   SOURCE   OF   SUPPLY. 


lO/ 


its  dimensions  and  shape,  may  more  properly  be  called  a  basin, 
and,  like  the  ordinary  circular  wells,  these  basins  may  be  either 
open  or  covered. 

A  second  method  of  collecting  the  ground  water  is  by  means 
of  a  covered  gallery  or  tunnel  constructed  in  part  of  porous 
material;  often  the  top  and  sides  are  built  of  tolerably  impervi- 
ous masonry  or  brickwork,  while  the  bottom  is  of  an  open  char- 
acter, so  that  the  water  which  rises  into  the  gallery  shall  come 
mainly  from  beneath.  An  example  of  this  now  quite  common 
mode  of  collection  is  at  Lowell,  Mass.*  The  "  filtering  gallery  " 
is  situated  on  the  northerly  shore  of  the  Merrimack  River  and 
parallel  with  it,  about  100  feet  from  the  water's  edge.  Its  length 
is  1,300  feet,  width  8  feet,  and  height  (inside)  8  feet.  The  side 
walls  have  an  average  thickness  of  2\  feet  and  a  height  of  5  feet, 
and  are  constructed  of  heavy  rubble  masonry,  laid  water-tight  in 
hydraulic  mortar.  The  walls  support  a  semicircular  brick  arch, 


mra  ^V,*V?  .:-> x^C  n«>» 

» 


FlG.    16. — FILTER   GALLERY,  LOWELL,    MASS.      (FROM   FANNING.) 

one  foot  thick,  made  water-tight.    Along  the  bottom,  stone  braces, 
one  foot  square  and  eight  feet  long,  are  placed,  ten  feet  from 


*  A  full  description  of  the  works  is  given  in  the  Fifth  Annual  Report  of  he 
Mass.  State  Board  of  Health.  Also,  in  the  Third  Annual  Report  of  the  Water  Com- 
missioners of  the  City  of  Lowell,  1873. 


IO8  WATER  SUPPLY. 

center  to  center,  between  the  walls,  to  keep  them  in  position. 
The  water  comes  in  at  the  bottom,  which  is  covered  with  screened 
gravel  and  small  stones. 

One  of  the  best  examples  of  a  filtering  gallery  m  th'is  country5 
is  that  which  supplies  the  city  of  Columbus,  Ohio.     This  gallery 
is  a  brick  and  cement  conduit,  36  by  42  inches,*and  is  shown  in 
process  of  construction  in  Figure  17.     It  is  in  all 


FlG.    17.— FILTERING  GALLERY,  COLUMBUS,    OHIO. 

length,  and  is  situated  in  the  gravel  deposit  at  the  junction  of 
the  Scioto  and  Olentangy  rivers.*  This  method  of  construction 
has  been  followed  also  at  Taunton,  Mass. 

A  third  method  is  to  substitute  for  the  collecting  gallery  a  line 
of  iron  pipes,  z>.,  practically  water-mains,  cast  with  a  great  number 
of  narrow  longitudinal  slits,  and  laid  with  loose  joints.  These 
pipes  collect  the  water,  and  conduct  it  to  receiving  wells,  from 
which  the  supply  is  pumped.  In  filling  the  trench  in  which  the 
pipes  are  laid,  the  pipes  are  surrounded  on  all  sides  with  coarse 
material,  of  too  large  a  size  to  fall  into  or  through  the  slits,  and 
the  trench  is  then  filled  with  screened  material  of  decreasing  size. 
Works  of  this  kind  are  in  use  in  various  places  in  Germany,  at 
Dresden,  Hanover,  etc.  At  Halle,  glazed  clay  pipes  are  em- 

*  Tenth  Annual  Report  of  the  Trustees  of  the  Water- Works,  Columbus,  O.,  1880. 


GROUND   WATER  AS  A   SOURCE   OF   SUPPLY. 


109 


ployed,  47  c.m.  in  diameter  and  2.8  m.  long ;  the  total  area  of 
the  slits  in  a  single  pipe  is 
equal  to    the    area   of   the 
cross  section   of   the  pipe. 
(See  Fig.  1 8.) 

Still  a  fourth  method 
consists  in  the  use  of  the 
"  driven  well,"  which  is  de- 
scribed on  page  1 12  and  fol- 
lowing pages,  but  as  wells 
of  this  description  are  fre- 
quently sunk  through  a 
layer  of  clay  into  a  stratum 
of  water  below  the  ground 
water  proper,  they  partake  i 
also  of  the  character  of 
"  artesian  wells,"  which  will 
be  considered  in  the  next 
chapter. 

FIG.  1 8.     (FROM  FISCHER.) 

The  Effect  of  Pumping  upon  the  Ground  Water. 

For  the  purposes  of  this  discussion,  we  will  suppose  that  the 
water-bearing  deposit  into  which  a  well  is  sunk  is  perfectly  homo- 
geneous. When 
no  water  is  re- 
moved, by  pump- 
ing orotherwise,* 
the  water  in  the 
well  stands  at  the 
same  level  as  in 
the  ground;  when 
pumping  begins, 
the  water  falls  at 


first    rapidly,    af- 
FlG-  I9-  terward       more 

slowly,  until — if  the  discharge  of  the  pump  be  uniform — a  point 


*  If,  as  is  exceptionally  the  case,  the  water  is  delivered  by  gravity,  the  effect  on 
the  ground  water  is  essentially  the  same  as  if  the  water  were  removed  by  pumping. 


110  WATER  SUPPLY. 

is  reached  where  the  water  is  supplied  at  exactly  the  same  rate 
as  delivered  by  the  pump.  Suppose,  in  Fig.  19,  that  the  water 
stood  originally  at  a  b,  and  that  an  equilibrium  has  been  estab- 
lished when  the  water  in  the  well  has  fallen  to  c.  The  water 
flows  from  the  gravel  into  the  well  by  virtue  of  the  head  or  dif- 
ference of  level  a  c,  but  its  flow  is  impeded  by  the  resistance  due 
to  interstitial  friction  against  the  particles  of  sand  or  gravel,  and 
the  water  surface  assumes  somewhat  the  form  indicated  by  the 
line  c  d.  The  line  c  d  approaches  a  b  until  it  finally  coincides  with 
it ;  that  is,  there  is  a  point  beyond  which  no  measurable  influence 
is  exerted  on  the  natural  level  of  the  ground  water,  and  its  dis- 
tance from  the  center  of  the  well  depends  upon  the  circumstances 
of  each  particular  case.  In  certain  experiments  made  by  Sal- 
bach  in  the  alluvial  deposit  on  the  banks  of  the  Elbe,  above 
Dresden,  it  was  found  that  when  the  water  in  an  experimental 
well  was,  by  pumping,  kept  constantly  2.5  meters  below  its  nor- 
mal level,  the  height  of  the  ground  water  was  measurably  affected 
in  every  direction  for  a  distance  of  some  60  meters  (say  200  feet). 
In  experiments  made  by  Piefke,  at  Berlin,  the  influence  of  the 
well  was  felt  to  a  distance  of  some  300  meters  in  wet  weather, 
and  to  over  700  meters  at  other  times  ;  but,  while  the  effect  could 
be  traced  to  that  distance,  it  was  very  small  at  the  extremity  of 
this  radius.  With  the  water  in  the  well  2.33  meters  below  the 
normal  level  of  the  ground  water,  there  was  a  lowering  of  only 
0.35  meter  at  a  distance  of  50  meters,  of  0.17  meter  at  a  dis- 
tance of  100  meters;  and  at  a  distance  of  260  meters  the  lower- 
ing was  through  only  o.io  meter.  In  the  Berlin  locality  the 
natural  movement  of  the  ground  water  was  very  slow,  and  524 
meters  from  the  river  the  water  stood  only  0.63  meter  above 
that  in  the  stream. 

Where  the  ground  is  homogeneous,  or  nearly  so,  and  the 
water  can  come  from  one  direction  as  easily  as  from  another,  we 
have  what  may  be  called  a  circle  of  influence,  with  the  center  of 
the  well  for  the  center  of  the  circle ;  but  if  the  deposit  is  not 
homogeneous,  as  is  often  the  case,  the  water  comes  more  easily 
from  one  direction  than  another,  and  the  effect  of  pumping  is 
felt  to  unequal  distances  from  the  well.  As  appears  from  Fig.  19, 
the  effect  of  the  flow  of  water  into  the  well  is  to  form  a  sort  of 
crater  from  which  the  water  is  drained.  This  is  often  spoken  of 
as  a  "  cone,"  but  it  is  not  a  cone,  strictly  speaking.  The  exact 


EFFECT  OF  PUMPING  ON  GROUND  WATER.  Ill 


form  of  the  curve  c  <^will  depend  upon  circumstances,  but  it  will 
always  lie  above  the  straight  line  joining  the  points  c  and  d. 

Returning  again  to  our  well,  if  pumping  ceases,  the  water  will 
gradually  flow  into  the  well  until  finally  it  has  found  its  level 
and  stands  as  in  the  surrounding  ground.  If,  on  the  other  hand, 
starting  with  the  water  in  the  well  at  c,  a  larger  quantity  be 
pumped  than  before,  the  level  in  the  well  will  fall,  and  as  c  sinks 
to  e,  the  water  in  the  ground  also  falls  and  the  surface  will  be 
indicated  by  e  f.  In  order  that  this  new  and  larger  quantity 
should  be  obtained,  the  circle  of  influence  must  become  also  en- 
larged, that  is,  a  larger  area  must  contribute  to  the  supply.  The 
absolute  quantity  of  water  which  can  be  obtained  from  any  well 
depends  upon  the  amount  of  rainfall  which  finds  its  way  into 
the  ground  water  of  the  region  from  which  the  well  draws  its 
supply.  If  the  deposit  were  in  a  basin,  and  no  water  came  from 
the  rain,  the  effect  of  pumping  would  be  to  gradually  exhaust 
the  water  :  thus,  if  the  water  in  the  well  were  kept  at  a  constant 
level,  say  at  c,  the  quantity  of  water  delivered  in  a  given  time 
would  grow  less  and  less,  and  finally  the  surface  of  the  ground 
water  would  be  a  horizontal  plane  passing  through  c  ;  if,  on  the 
contrary,  a  constant  quantity  were  pumped,  the  water  in  the  well 
would  sink  lower  and  lower  until  the  bottom  was  reached,  and 
the  further  delivery  of  the  same  quantity  would  be  impossible. 
Practically,  wells  are  not  sunk  in  such  a  deposit,  but  in  one 
where  the  ground  water  is  continually  receiving  accessions  from 
the  rain  or  melting  snow,  or,  in  some  cases,  from  a  neighboring 
stream.  The  amount  which  can  be  obtained  from  any  deposit 
depends  finally  on  the  amount  received,  and  no  such  well,  how- 
ever great  its  diameter  or  its  depth,  can  be  inexhaustible,  although 
practically  it  may  never  be  called  upon  to  furnish  more  than  it 
can  supply. 

A  good  illustration  of  the  effect  of  a  constant  draught  in 
permanently  lowering  the  level  of  the  ground  water  is  afforded 
by  the  well  in  Prospect  Park,  Brooklyn,  N.  Y.  The  well  was 
constructed  in  1869. 

The  elevation  of  water  table  as  first  found,  Nov.,  1868,  was.  ..15.6  ft.  above  tide  level. 
Elevation  of  water  table,  May,  1879  .......................  15.2  "  " 

Elevation  of  water  table  on  completion  of  the  well,  Dec.,  1869.14.55          "  " 

Pumping  began  regularly  on  June  5,  1870;  the  effect  has  been 
as  follows: 


112 


WATER   SUPPLY. 


Average  Number  of 
Gallons  per  Day. 

Average  Elevation 
of  Water  Table. 

300,000 

1415 

272,000 

13.03 

437,000 

10.56 

288,000 

11.29 

333,ooo 

10.70 

294,000 

9.83 

235,000 

9.83 

252,000 

9.2I 

Year. 
1870 
1871 

1872 

1873 
1874 

1875 
1876 

1877 

It  is  seen  here  that  an  average  draught  of  only  304,000  gal- 
lons per  day  has  lowered  the  water  table  five  feet  in  eight  years, 
and  also  that  the  yield  is  diminishing,  for  while  in  1873  a  daily 
draught  of  288,000  gallons  permitted  the  water  table  to  rise  five 
inches,  in  1876  a  draught  of  235,000  gallons  was  just  equal  to  the 
supply,  and  in  1877  a  draught  of  252,000  gallons  again  lowered 
the  water.* 

In  the  previous  discussion  we  have  spoken  of  a  single  well  of 

ordinary  diame- 
ter. If  a  series 
of  wells  be  locat- 
ed near  each 
other,  the  effect 
will  be  essen- 
tially the  same, 
FIG.  20.  except  the  circle 

of  influence  will  become  approximately  an  ellipse,  as  would  be 
the  case  if  several  wells  were  connected  so  as  to  form  an  open 
basin  or  a  covered  gallery.  In  locating  a  series  of  wells,  reference 
should  be  had  to  the  character  of  the  water-bearing  deposit,  in 
order  that  they  may  not  be  placed  unnecessarily  near  together. 

Driven   Wells. 

"  Driven  "  wells,  "  tube "  wells,  or  as  they  are  sometimes 
called  abroad,  "  American  "  or  "  Abyssinian  "  wells,  f  are  formed 
by  forcing  wrought-iron  (or  galvanized  iron)  tubes,  such  as  are 
used  for  gas  or  water  pipes,  down  into  the  stratum  from  which 

*  Croes  and  Howell,  Newark  Aqueduct  Board  :  Report  on  Additional  Supply, 
1879,  p.  61. 

f  Also  called  *•  Norton "  wells,  the  English  patent  having  been  taken  out  by  a 
Mr.  J.  L.  Norton. 


DRIVEN  WELLS.  113 

the  water  is  to  be  taken.  The  pipes  are  generally  from  iK  to  2 
inches  in  diameter,  and  furnished  at  the  lower  end  with  a  wrought- 
iron  or  steel  point ;  above  this  point  the  pipes  are  perforated  for 
some  distance  with  holes  to  admit  the  water.  The  pipes  with 
point  attached  may  be  driven  with  a  mallet  or  falling  weight, 
and  when  the  top  of  one  tube  has  reached  the  surface  of  the 
ground,  a  second  length  is  attached  to  it  with  a  common  coup- 
ling, and  the  driving  continued  to  the  desired  depth.  In  many 
localities  it  is  better  to  first  drive  down  a  suitable  steel-pointed 
rod  or  drill  until  water  is  reached,  and  to  insert  the  well-tube  in 
the  hole  thus  made.*  In  the  perforated  points  for  such  wells, 
the  greatest  variety  exists,  it  being  stated  that  about  150  patents 
have  been  issued  for  points  and  cognate  portions  of  the  pipe. 
The  figure  represents  that  known  as  Andrews'  Patent. 


FlG.    21. — DRIVEN   WELL  POINT. 

Although  pipes  of  larger  dimensions  than  those  mentioned 
are  sometimes  driven,  it  is  usual  when  a  large  amount  of  water 
is  required — as  for  manufacturing  purposes  or  for  town  sup- 
ply— to  drive  a  number  of  wells  in  the  same  limited  area,  and 
connect  them  to  a  common  suction  pipe  leading  to  the  pump. 
The  driven  well  partakes  of  the  character  of  the  shallow  well 
when  its  source  of  supply  is  the  ground  water,'  but  it  often  par- 
takes of  the  character  of  the  artesian  well,  as  when  it  is  driven 
through  a  layer  of  clay  or  other  impervious  material  underlying 
the  ground  water  into  another  water-bearing  stratum  below. 

When  a  driven  well  is  forced  into  the  ground  water,  and 
water  is  removed  by  pumping,  the  effect  is  essentially  the  same 
as  has  already  been  described  (pages  109-112)  with  an  open 
well.  The  driven  well  is  valuable  as  a  means  of  obtaining  water 
on  account  of  facility  of  construction,  but  it  involves  no  princi- 

*  Both  methods  of  constructing  the  driven  well  are  covered  by  the  Reissue  Let- 
ters Patent  (No.  4,372)  granted  to  Nelson  W.  Green,  May  q,  1871,  and  the  validity  of 
the  patent  has  been  affirmed  by  several  legal  decisions.  It  is  claimed,  however,  that 
the  patent  is  antedated  by  a  U.  S.  Patent  granted  to  James  Suggett,  March  29,  1864, 
and  by  British  Letters  Patent  granted  to  John  Goode,  Oct.  16,  1823. 
8 


WATER   SUPPLY. 


pie  which  is  new  as  far  as  bringing  the  water  to  the  surface  is 
concerned. 

It  is  asserted  that  a  driven  well  differs  from  an  ordinary  well 
in  two  essential  respects.  In  the  first  place,  the  well,  which  is 
always  of  very  small  diameter,  is  not  dug  or  bored,  but  sunk  with- 
out removal  of  the  earth  *  in  the  manner  already  described,  either 
directly  or  by  first  driving  down  an  iron  rod,  and  after  its  re- 
moval, inserting  the  well  tube ;  in  either  case  the  result  is  a  nar- 
row well  with  air  tight  walls,  fitting  closely  in  the  earth  about  it : 
the  tube  is  the  well.  It  is  further  asserted  that  when  a  suction  pump 
is  attached  to  the  pipe  a  new  element  is  introduced,  and  peculiar 
effects  are  produced  by  "exhausting  the  air,"  or  "producing  a 
vacuum,"  and  that  thus  the  water  is  drawn  to  the  pump  by  a 
force  independent  of  gravity,  and  to  which  gravity  is,  in  this 
case,  but  auxiliary. 

These  claims  are,  however,  fallacious.  The  diagram,  Fig.  22, 
may  represent  the  suction  pipe  of  a  pump  inserted  in  a  narrow 

open   well,    the 
A*&     *&f  /'      normal   level  of 
the  ground  wa- 
ter being  at  ab. 
Now,    although 
with    a     driven 
well  much  stress 
is  laid  upon  the 
*  "  air-tight"  tube, 
'"*  it    is    the    tube 
alone  that  is  air- 
tight, as  any  suc- 
tion  pipe   must 
practically    b  e . 
The  soil,  even  if 
compacted 
about  the  tube, 
is  not   air-tight, 
and  as  far  as  transmitting  pressure  goes,  the  air  which  is  about 


FIG.  22. 


*  This  is  Col.  Green's  method,  but  well  tubes  are  also  driven  into  the  earth  at  the 
same  time  that  their  passage  is  facilitated  by  forcing  into  the  tube,  which  in  this  case, 
is  open  at  the  bottom,  a  stream  of  water.  This  water  washes  out  and  brings  to  the 
surface  the  sand  and  clay  from  the  bottom  in  advance  of  the  driving. 


DRIVEN   WELLS.  1 15 

the  tube  in  Figure  22,  and  which  rests  on  the  surface  of  the  water 
at  #,  is  in  no  different  condition  whether  the  tube  be  in  natural 
ground,  or  in  a  dug  well,  as  indicated  in  the  figure.  The  air  circu- 
lates freely  in  the  ground ;  it  responds  at  once  to  any  change  in  the 
barometric  pressure,  and  at  once  takes  the  place  of  any  water 
which  may  be  removed  from  the  interstices  of  the  soil.  Again, 
below  the  water-level,  the  water,  like  the  air  above,  circulates, 
although  less  freely,  owing  to  interstitial  friction,  and,  of  course, 
fills  all  the  pores  of  the  ground  close  up  to  and  around  the  pipe. 
The  statement  that  the  pipe  is  the  well,  is  misleading.  If  we 
start  (Fig.  22)  with  the  tube  as  a  suction  pipe  in  an  open  well, 
and  imagine  the  well  to  be  gradually  narrowed  in  diameter  by 
filling  in  around  the  circumference,  the  tube  will  continue  to  be 
practically  a  suction  pipe,  even  when  the  well  has  been  finally 
filled  up — the  well  finally  having  become  a  hollow  cylinder  of 
water,  of  the  thickness  of  a  mere  film  if  the  soil  is  very  compact. 
It  is  quite  inconceivable  that  the  filling  of  the  well  with  gravel  or 
sand,  no  matter  how  closely  compacted  the  sand  may  be,  could 
produce  any  other  effect  than  that  due  to  the  increased  resist- 
ance to  the  passage  of  water  in  the  annular  space  about  the  suc- 
tion pipe. 

To  show  further  the  fallacy  of  the  claims  alluded  to,  let  us 
return  to  Fig.  22,  in  which  the  normal  level  of  the  ground  water 
is  represented  at  a  b.  If,  now,  a  given  quantity  of  water  be  taken 
continually  from  the  point  c,  in  a  given  interval  of  time,  the  slope 
c  d,  which  the  water  surface  will  assume,  will  be  precisely  the 
same  whether  the  water  is  drawn  in  buckets,  or  by  a  tube  in  an 
open  well,  or  by  a  driven  well,  because  the  same  amount  of  water 
rqust  reach  the  same  point  c  in  the  same  time,  and  starting  from 
the  same  original  position.  If  the  claim  be  true  that  more  water 
can  be  obtained  by  one  method  than  by  another,  it  follows  that 
the  water  must  be  supplied  faster  in  one  case  than  in  the  other, 
and  there  are  two  necessary  consequences :  first,  if  the  point  c 
remains  unchanged,  this  increased  rapidity  of  flow  must  result  in 
an  alteration  of  the  slope  of  the  water  surface.  On  the  other 
hand,  if  the  quantities  pumped  in  the  same  time  are  made  equal, 
then  in  the  first  case  the  point  c  will  not  fall  as  low  as  in  the 
second. 

While  we  should  reject,  a  priori,  the  consequences  to  which 
these  assumptions  necessarily  lead,  recent  experiments  made  by 


WATER  SUPPLY. 

Mr.  J.  C.  Hoadley  *  show  that  the  slope  is  the  same  whether  the 
given  yield  of  water  be  from  an  open  well  or  from  a  driven  tube ; 
and  that,  with  the  same  delivery,  the  level  of  the  water  in  the 
well  or  pipe  is  lowered  to  the  same  point.  The  particular  exper- 
iment alluded  to  was  performed  as  follows :  A  3-inch  open  pipe 
was  driven  in  pervious  soil,  into,  and  considerably  below  the  sur- 
face of  the  ground  water,  forming  an  open  well — the  earth  being 
removed  from  within.  Into  this  pipe  a  suction  pipe  of  i^-inch 
diameter  was  dropped  and  wedged  into  position,  so  as  not  to 
close  the  opening  of  the  3-inch  pipe.  Water 
was  pumped  for  a  certain  time,  as  much  as 
the  well  would  supply.  Subsequently,  by 
means  of  a  cap,  the  suction  tube  was  se- 
cured in  the  3-inch  pipe  and  the  opening  of 
the  latter  pipe  hermetically  sealed.  The 
suction  pipe  thus  became,  practically,  a 
driven  well.  Under  these  circumstances, 
every  other  condition  being  unchanged,  the 
yield  of  water  was  approximately  the  same 
as  in  the  previous  case,  the  slight  difference 
which  existed  being  in  favor  of  the  open 
well. 

It  should  be  noted  that  in  what  has  been 
said  above,  the  yield  of  a  driven  well  is  com- 
pared with  that  of  a  dug  well  of  no  great 
FIG.  23.  diameter.     If   the  well  be  increased  in  di- 

ameter to  30,  50,  or  100  feet,  so  that  the  distance  c  c'  (Fig.  22), 
becomes  considerable,  the  limit  of  measurable  effect  on  the  ground- 
water  level  will  be  removed  farther  from  a,  and  the  yield  of  the 
well  will  be  appreciably  greater — or,  in  other  words,  with  the 
same  delivery,  the  point  c  will  not  fall  so  low. 

With  regard  to  the  absolute  amount  of  water  which  can  be 
utilized  in  a  given  locality,  common  sense,  as  well  as  science,  tells 
us  that  the  amount  of  water  which  a  given  deposit  can  furnish 
must  be  a  definite  quantity,  although  to  us  unknown ;  and  al- 
though the  driven  wells  may  enable  us  to  obtain  this  water  more 
conveniently  than  other  methods,  the  absolute  amount  obtain- 
able is  no  greater,  and  the  supply  cannot  be  inexhaustible,  as 

*  Private  communication :  this  statement  is  absolutely  true  only  when  the  wells 
are  of  the  same  diameter. 


NATURAL  FILTRATION. 

some  of  the  enthusiastic  advocates  of  the  driven-well  system 
would  have  us  believe.  One  'great  advantage  which  the  driven 
wells  possess  is  the  facility  with  which  they  may  be  sunk  for 
experiment  or  temporary  use.  For  example,  they  were  exten- 
sively used  by  the  British  army  in  the  Abyssinian  expedition, 
1867-68  ;  and  hence,  in  England,  they  are  frequently  called  Abys- 
sinian wells. 

It  should  also  be  noted  that  the  driven  well  ordinarily  takes 
its  water  from  a  lower  point  than  that  to  which  a  dug  well  would 
be  sunk  in  the  same  locality.  For  this  reason,  a  driven  well  may 
continue  to  furnish  water  when  a  neighboring  dug  well  has  be- 
come dry,  and  thus  the  impression  that  the  driven  well  is  inex- 
haustible gains  ground. 

On  this  account  also,  the  driven  well  is  somewhat  less  liable 
to  pollution  than  a  dug  well  in  the  same  locality,  as  the  polluting 
material  may  be  rather  more  diluted  in  the  mass  of  the  ground 
water.  Moreover,  as  has  been  said,  the  driven  well  often  passes 
through  an  impervious  stratum  of  clay,  so  that  the  water  ob- 
tained is  entirely  distinct  from  the  ground  water  of  the  locality. 
In  this  way  good  water  may  sometimes  be  obtained  where  the 
surface  conditions  are  very  unfavorable,  but  there  is  always  an 
element  of  risk  involved  in  sinking  a  well  among  sources  of  pol- 
lution. 

"Natural  Filtration." 

The  ultimate  source  of  the  ground  water  is  the  rain,  and  that 
the  rain  is  the  proximate  source  of  the  water  obtained  from  a 
well  sunk  into  a  gravel  deposit  far  removed  from  any  stream  or 
pond,  scarcely  any  one  can  doubt.  Such  a  well  is  that  in  Pros- 
pect Park,  Brooklyn,  alluded  to  on  page  in.  This  well  is  nearly 
two  miles  from  tide-water,  and,  although  the  natural  level  of  the 
water  has  been  lowered  by  pumping,  it  is  still  a  number  of  feet 
above  tide  level.  Generally,  however,  a  gathering  well,  basin,  or 
gallery  is  located  near  a  lake  or  river.  This  location  is  chosen 
mainly  because  at  such  a  place  there  is  almost  always  a  decided 
movement  of  the  ground  water  toward,  or  in  the  same  direction 
as,  the  stream  ;  but  such  a  location  is  also  chosen  in  order  that 
the  river  may  make  up  any  deficiency  caused  by  the  removal  of 
the  ground  water. 

It  was  formerly  supposed,  and  is  so  even  now,  by  many  per- 


Il8  WATER  SUPPLY. 

sons  who  have  not  made  a  study  of  the  subject,  that  in  sucn 
cases  the  water  is  derived  directly  from  the  river,  and  filtered  by 
passing  through  the  intervening  sand  and  gravel.  Undoubtedly, 
in  some  cases,  a  considerable  proportion  is  thus  derived,  but,  as  a 
rule,  the  contrary  is  true,  and,  where  the  location  is  such  that 
most  of  the  water  must  come  from  the  visible  body  of  water, 
the  supply  generally  proves  inadequate.  The  beds  of  ordinary 
streams  furnish  a  poor  filtering  surface,  and  the  experience  with 
artificial  filters  shows  how  soon  an  originally  clean  surface  be- 
comes clogged.* 

That  the  view  just  expressed  is  correct,  appears  from  a  va- 
riety of  considerations.  From  the  discussion  of  the  effect  of 
pumping  on  the  ground  water  (pages  109-112),  it  is  evident  that, 
from  a  well  situated  near  a  stream,  a  certain  amount  of  water 
can  be  drawn  without  calling  upon  the  stream  at  all  for  supply ; 
if,  however,  the  circle  of  influence  includes  a  portion  of  the 
stream,  some  of  the  water  may  come  from  this  source,  unless,  as 
is  indeed  generally  the  case,  it  is  easier  for  the  water  to  come  a 
greater  distance  through  open  water-bearing  deposits  than  to 
force  its  way  through  the  silted-up  and  more  or  less  impervious 
bed  of  the  stream. 

If  we  consider  the  character  of  the  water,  there  are  certain 
general  facts  that  are  at  once  and  readily  noticeable  :  the  water 
thus  obtained  is  generally  clear  and  colorless  ;  it  is  of  a  quite 
uniform  temperature,  cool  therefore  in  summer,  and  in  winter 
much  warmer  than  the  water  of  neighboring  ponds  and  rivers, 
which,  of  course,  approach  in  temperature  very  close  to  the 
freezing  point ;  the  water  also  differs  in  chemical  character  from 
that  of  neighboring  streams  or  ponds,  generally  being  somewhat 
harder. 

With  regard  to  the  temperature,  the  difference  is  very  marked, 
even  where  the  water  is  collected  in  an  open  basin  and  thus 
exposed  to  the  heating  (or  cooling)  influences  of  the  air.  For 
instance,  in  the  filtering  gallery  at  Lowell,  Mass.,  during  the 
month  of  September,  1873,  the  highest  temperature  was  50°  F., 
the  lowest  49°  F.  ;  during  the  month  of  October,  observations 

""  The  term  natural  filtration  is  objectionable  only  so  far  as  it  implies  that  the 
water  is  obtained  from  the  lake  or  stream  by  a  process  of  filtration  :  that  the  rain  fall, 
ing  upon  the  ground  may  be  said  to  be  filtered  naturally  by  passing  through  the  inter- 
stices of  the  water-bearing  deposits  is,  of  course,  true. 


NATURAL  FILTRATION.  1 19 

were  made  on  thirteen  different  days  showed  identically  the 
same  temperature,  namely,  50°  F.  Between  September  6  and 
January  I,  the  highest  recorded  observation  is  52°  F.,  on  No- 
vember 8,  and  the  lowest  is  47°  F.,  December  31.  There  is  no 
corresponding  record  of  the  temperature  of  the  river,  nor  is  such 
necessary,  as  every  one  knows  that  river  water  varies  with 
the  temperature  of  the  surrounding  air,  and  in  December  must 
have  been  nearly  at  the  freezing  point.  At  Waltham,  Mass., 
where  the  water  is  taken  by  means  of  an  open  shallow  basin, 
more  marked  differences  have  been  observed  between  the  tem- 
peratures at  different  seasons.  Thus  in  winter,  when  the  river 
was  frozen,  the  temperature  in  the  basin  was  about  44°  F.,  and 
the  average  of  nineteen  observations  made  at  intervals  from 
August  23  to  August  26,  showed  for  the  river  an  average  tem- 
perature of  74°.  i  F.,  and  for  the  basin  water  an  average  tempera- 
ture of  62°. 8  F.  Such  instances  might  be  multiplied  indefinitely, 
and  it  seems  quite  impossible  to  account  for  the  observed  differ- 
ences by  the  continuous  passage  of  water  through  100  feet  or  so 
of  gravel.  In  fact  where  no  such  differences  are  observed,  it  may 
be  a  sign  that  the  water  does  come  from  the  stream,  and  the 
water  is  likely  to  be  otherwise  unsatisfactory  ;  thus  the  city  of 
Toulouse,  in  France,  is  supplied  by  a  number  of  filtering  gal- 
leries in  a  gravel  deposit  on  the  banks  of  the  Garonne.  The 
original  gallery  was  built  in  182-  at  a  distance  of  about  60  meters 
(200  feet)  from  the  river.  This  furnished  water  acceptable  in 
quality,  but  deficient  in  quantity ;  an  increase  of  the  length  of 
the  gallery  failed  to  furnish  a  corresponding  increase  in  quantity 
of  water  obtained.  A  second  filtering  gallery,  or  rather  series  of 
connected  wells,  was  constructed  nearer  to  the  river,  at  a  distance, 
in  fact,  of  only  ten  meters.  In  this  case,  the  water  obtained  man- 
ifestly did  come,  in  part  at  any  rate,  from  the  river :  the  water 
was  somewhat  turbid,  and  what  is  very  instructive,  the  passage 
through  a  bank  of  thirty  feet,  and  admixture,  of  course,  with 
some  ground  water,  failed  to  bring  the  water  to  anything  like 
the  uniform  temperature  of  the  other  galleries.  The  tempera- 
ture fell  in  winter  to  2°  C.  (35°.6  F.),  and  in  summer  rose  above 
21°  C.  (70°  F.).*  This  gallery  was  therefore  abandoned,  and 
others  constructed  at  a  greater  distance  from  the  stream.  These 

*  D'Aubisson.     Annales  des  Fonts  et  Chaussees,  1838. 


I2O  WATER  SUPPLY. 

furnish  water  which  is  satisfactory,  except  when  in  time  of  flood 
the  river  covers  the  whole  territory  in  which  the  galleries  are 
built,  and  the  galleries  become  filtering  galleries  in  the  true 
sense. 

As  marked  differences  as  in  the  matter  of  temperature  are 
also  observed  in  the  chemical  character  of  the  water.  This  often 
appeals  to  the  eye  by  the  absence  of  color  in  the  (so-called)  fil- 
tered water,  while  the  water  of  the  river  may  be  strongly  colored  ; 
or,  if  the  gallery  be  alongside  of  a  pond,  the  latter  may  be  filled 
with  algae  in  a  state  of  decomposition,  without  producing  the 
slightest  effect  on  the  gallery  water.  It  is,  however,  the  hardness 
of  the  water  which  generally  attracts  attention,  being  noticed 
where  the  water  is  used  for  washing  or  in  steam  boilers.  Usu- 
ally the  ground  water  is  harder  than  the  surface  water  of  the 
same  region,  but  occasionally  the  reverse  is  true.  Belgrand  gives 
a  number  of  examples  from  French  localities,  from  which  may 
be  cited  the  following :  * 

Water  of  Rhone,  at  Lyons 16° 

Water  of  filtering  gallery  at  Lyons 17-94 

Water  of  Loire,  at  Nevers 4.96 

Water  of  collecting  well 20. 70 

Water  of  Loire,  at  Blois 7. 76 

Water  of  the  gallery  (which  is  beneath  the  bed  of  the  river) 14-45 

Sharpies  has  found  f  that  the  water  in  the  filter  gallery  near 
Little  Pond,  Cambridge,  contains  nearly  twice  as  much  lime  as 
that  of  the  pond,  and  instances  might  be  multiplied  indefinitely. 
In  the  case  of  the  Dresden  water  supply  the  river  water  is  harder 
than  that  obtained  from  the  collecting  wells.  \ 

Even  when  the  gallery  or  well  is  sunk  directly  in  the  bed  of 
the  river,  or  in  an  island  surrounded  on  all  sides  by  the  river  or 
pond,  the  ground  water  still  contributes  largely  or  wholly  to  the 
supply.  Many  experiments  have  shown  that  the  water  in  a 
gravel  deposit  directly  beneath  a  river  differs  essentially  from 
that  of  the  stream  itself. 

The  belief  that  a  well  or  gallery  located  near  a  pond  or  stream 

*  La  Seine,  etc. ,  pp.  463  and  following. 

f  Twelfth  Annual  Report  of  the  Cambridge  Water  Board,  for  the  year  1876. 
Boston,  1877  ;  page  30. 

\  Salbach.     Das  Wasserwerk  der  Stadt  Dresden  ;  yc  Theil,  page  7. 


NATURAL   FILTRATION.  121 

does  not  necessarily  derive  its  supply  from  the  visible  body  of 
fresh  water,  finds  confirmation  in  the  well-known  fact  that  springs 
are  often  observed  to  issue  from  the  sand  along  the  sea  shore, 
even  below  low-water  mark,*  and  fresh  water  is  often  obtained 
by  sinking  wells  very  near  the  shore.  Generally,  in  such  cases, 
the  surface  of  the  ground  and  the  water  table  rise  as  they  recede 
from  the  shore,  the  ground  water,  derived  from  the  rain,  passing 
with  more  or  less  resistance  to  the  sea.  In  such  wells,  the 
water  rises  and  falls  with  the  tide,  as  the  water  must  enter  the 
sea  under  the  pressure  of  a  varying  height  of  salt  water,  but  the 
salt  water  itself  does  not  penetrate  the  soil  and  reach  the  well 
itself.  From  such  wells  a  certain  amount  of  water  can  be 
pumped.  If  the  amount  pumped  exceeds  that  which  the  ground 
water  can  furnish,  salt  water  may  then  be  drawn  into  the  con- 
tributing area,  and  the  water  become  brackish.  Even  where  the 
ground  near  the  sea  is  level,  the  mere  effect  of  the  rain  falling 
upon  the  sandy  area  is  sufficient  to  create  a  deposit  of  fresh 
water  which  may  crowd  out  or  prevent  the  entrance  of  salt  water. 
Darwin,  in  the  voyage  of  the  "  Beagle,"  discovered  this  to  be 
the  case  in  low  coral  islands  of  the  Pacific,  close  to  the  sea ;  and 
in  Holland,  Amsterdam,  the  Hague  and  Leyden  obtain  their 
water  from  collecting  canals  in  the  sand-dunes  which  form  an 
almost  barren  strip  of  country  from  2  to  5  kilometers  wide,  hav- 
ing only  a  few  elevations  of  surface.  Sometimes  fresh  water 
overlies  the  salt,  so  that  shallow  wells  furnish  fresh  water,  while 
deeper  wells  give  brackish  or  salt  water.  McAlpine  has  made 
the  interesting  observation  that  where,  as  on  Long  Island,  N.  Y., 
the  water  table  slopes  down  to  the  sea,  the  underlying  deposit 
of  salt  water  slopes  away  from  the  sea — the  higher  and  conse- 
quently heavier  column  of  fresh  water  at  some  distance  inland 
being  able  to  displace  the  salt  water  to  a  greater  depth  :  thus, 
the  vertical  section  of  the  body  of  fresh  water,  in  the  direction 
of  its  flow,  would  be  that  of  an  elongated  wedge.  Salt  water 
has  been  found  underlying  the  fresh  water  in  other  localities — 

*  A  remarkable  example  of  this  occurs  at  the  four  iron  forts  at  Spithead,  Eng. 
Here  wells  are  sunk  on  artificial  islands,  at  a  considerable  distance  from  the  shore, 
and,  although  two  of  them  are  over  550  feet  deep,  they  pass  entirely  through  sand  and 
gravel.  In  spite  of  this  location,  the  water  of  the  wells  contains  only  a  small  proper- 
tion  of  chlorine  (18.6,  11.4,  4.1,  7.6  parts  in  100,000  respectively),  showing  that 
almost  no  sea  water  finds  its  way  into  the  wells.—  The  Analyst,  April,  1883. 


122  WATER   SUPPLY. 

for  instance,  at  Hull,  in  England  * — where  the  salt  water  is  sup- 
posed to  be  due  to  the  infiltration  of  sea  water,  and  not  to  the 
mineral  character  of  the  rock. 

Preliminary  Examination  of  a  Proposed  Ground  Water  Supply. 

The  least  satisfactory  point  in  connection  with  ground-water 
supplies  is  that  the  amount  of  water  to  be  obtained  in  any  one 
locality  is  limited  in  amount,  and  it  is  very  difficult  to  tell  in 
advance  how  large  an  amount  a  given  region  can  be  relied 
upon  to  supply,  except  as  a  result  of  thorough  surveys  and  long- 
continued  experiments. 

The  effect  of  pumping  upon  the  level  of  the  ground  water 
and  information  as  to  the  direction  of  its  flow  may  be  obtained 
by  driving  a  number  of  iron  pipes  with  perforated  "  points  "  at 
regular  distances,  preferably  in  two  lines  at  right  angles  to  each 
other,  intersecting  in  the  experimental  well.  Observations  should 
be  made  on  the  natural  level  of  the  ground  water  before  pump- 
ing is  begun ;  and  the  pumping  is  best  conducted  by  keeping  the 
level  of  the  water  in  the  well  at  a  constant  distance  below  the 
natural  level  of  the  ground  water,  or  below  the  level  of  the  water 
in  the  pond  or  stream.  Although  absolute  equilibrium  cannot 
be  established  for  a  considerable  time,  unless  the  water  comes 
very  freely,  and  in  the  absence  of  rain,  sufficient  indications  can 
be  obtained  to  form  judgment,  within  limits,  as  to  the  probable 
yield  of  the  well.  In  locating  a  gallery  or  elongated  basin,  refer- 
ence will  be  had  to  the  direction  of  the  greatest  movement  of 
the  ground  water,  which  is  sometimes  in  the  direction  of  the  flow 
of  the  visible  stream  and  sometimes  at  right  angles  to  it. 

A  preliminary  examination  with  reference  to  a  future  supply 
should  include  a  careful  survey  of  the  entire  drainage  area,  and 
in  all  cases  the  preliminary  examinations  should  be  made  by 
those  conversant  with  the  matter,  as  there  is  great  liability  to 
overestimate  the  probable  yield  of  water.  As  a  rule,  the  amount 
obtained  from  any  such  well  is  greater  at  first,  as  it  requires  time 
to  drain  out  the  water  naturally  occupying  the  territory  which 
hereafter  is  to  flow  into  the  well.  On  the  other  hand,  the  effect 
of  the  draught  of  water  toward  a  single  point  is  to  open  chan- 
nels in  the  porous  material  so  that  in  some  cases  the  yield 

*  Proc.  Inst.  Civ.  Eng.  Gr.  Br.,  Iv,  p.  257. 


EXAMINATION   OF   GROUND   WATER.  123 

increases  with  time.  Besides  an  assurance  that  the  quantity  of 
water  obtainable  is  and  will  be- sufficient,  it  is  necessary  to  know 
that  the  water  is  satisfactory  in  quality.  As  far  as  the  character 
of  the  water  is  concerned,  it  is  in  New  England  generally  good 
when  sufficiently  abundant  ;  it  is  almost  always  harder  than  the 
river  water,  but  in  most  localities  this  difference  in  hardness  is 
small,  although  appreciable.  In  limestone  regions,  however,  the 
ground  water  is  often  so  hard  as  to  be  unsuited  for  use  ;  and 
sometimes  the  presence  of  streaks  or  beds  of  clay  or  of  ochre 
makes  it  impossible  to  obtain  clear  water. 

The  absence  of  such  injurious  deposits  should  be  ascertained, 
not  only  at  the  point  at  which  it  is  proposed  to  locate  the  actual 
well  or  gallery,  but  also  in  the  immediate  neighborhood,  espe- 
cially in  the  directicn  in  which  the  gallery  is  likely  to  be  ex- 
tended or  where  additional  wells  may  be  sunk. 

Leipzig,  in  Germany,  has  had  a  ground-water  supply  since 
1866.  The  water,  which  was  of  good  quality,  proved  insufficient 
for  the  wants  of  the  city,  and  the  supply  was  increased  (1871-72) 
by  the  construction  of  an  additional  collecting  gallery.  Appar- 
ently the  work  was  done  without  sufficient  preliminary  examina- 
tion, for  the  works  were  scarcely  opened  before  trouble  was 
experienced,  and  it  was  found  that  the  locality  into  which  the 
gallery  had  been  extended  was  generally  unsuitable.  There  was, 
however,  one  peculiar  and  instructive  difficulty.  The  gravel  of 
the  deposit  in  which  the  gallery  was  located  contained — as  grav- 
els frequently  do — oxide  of  iron.  This  ordinarily  would  give  no 
trouble,  but  the  gallery  intersected  an  old  river-bed  containing 
many  partially  decayed  stumps  and  other  organic  matter  which, 
in  the  presence  of  water,  reduced  the  oxide  of  iron  to  the  pro- 
toxide condition,  forming  soluble  protosalts  of  iron.  These  com- 
pounds dissolving  in  the  ground  water,  found  their  way  into  the 
collecting  gallery  in  large  quantity.  As  soon  as  these  soluble 
protosalts  of  iron  come  into  contact  with  the  air  they  are  oxi- 
dized, and  a  deposit  of  the  red  hydrated  oxide  is  formed.  In 
Leipzig  the  oxidation  generally  took  place  before  the  water 
reached  the  consumers,  and  the  complaint  was  with  reference  to 
the  muddy,  red  appearance  of  the  water  when  drawn ;  this  was 
easily  overcome  by  filtration.  Sometimes,  however,  the  water 
reached  the  consumers  before  the  oxidation  was  complete,  in 
which  case  the  filtered  water  tasted  "  like  ink,"  and  on  standing 


124 


WATER  SUPPLY. 


deposited  a  further  quantity  of  a  red  sediment.*  It  may  be 
stated  that  the  remedy  in  this  case  consisted  in  seeking  a  new 
supply  in  a  more  favorable  locality. 

As  we  have  seen,  even  where  a  well  or  gallery  is  located  near 
a  stream  or  pond,  the  proportion  of  water  received  from  the 
visible  stream  or  pond  is  usually  small ;  therefore,  to  obtain  in- 
formation as  to  the  character  of  the  water  to  be  obtained,  it  is 
much  more  important  to  examine  the  ground  water  than  the 
water  of  the  river.  The  examination  of  the  latter  should  not, 
however,  be  neglected,  and  it  would  scarcely  ever,  if  ever,  be 
advisable  to  locate  "  natural  filtration  "  works  on  the  banks  of  a 
stream  which  was  seriously  polluted. 

Further,  although  there  is  less  liability  to  pollution  than  in 
the  case  of  small  shallow  wells  sunk  near  dwellings,  slaughter 
houses,  factories,  or  stables,  it  must  be  remembered  that  the 
ground  water  is  fed  by  the  percolation  into  it  of  the  atmospheric 
water,  and  that  it  is  possible  to  pollute  even  a  large  body  of  water. 
This  fact  should  be  taken  into  account  in  choosing  a  locality  for 
the  collecting  wells. 


TABLE  XVII.— EXAMINATION  OF  GROUND  WATER. 

[Results  expressed   in  Parts  per  100,000.] 


Q- 

Q 

I 

J 

i< 

a 

LOCALITY. 

£>5 
J 

i 

n 

z 
5 

AUTHORITY. 

i 

I 
I 

Ss 
« 

s 

X 

H 

< 

3 

U 

o  008 

o  008 

W.  R  Nichols 

Newton,  Mass.,  basin  near  Charles  River,  1877  

3-9 

o. 

0.002 

0.3 

J.  M.  Merrick 

Taunton,  Mass.,  basin,  Aug.,  1877  

5.6 

0.009 

0.010 

W.  R.  Nichols 

5  8 

O.O2I 

Waltham,  Mass.,  basin,  Dec.,  1873  
"       river,     **        **        

6.5 
5  7 

0.005 

0.006 

0.4 

u 

Lowell,  Mass.,  gallery,  Jan.,  1874  

6.4 

0.006 

0.003 

0.3 

u 

"      river,       u       "    . 

Cambridge,  Mass.,  gallery,  Dec.,  1876  •          .... 

18.6 

o  080 

O.OO5 

3.1 

S.  P.  Sharpies 

pond,         '•       "    

14.0 

0.070 

O.OIO 

J-7 

IO.2 

o 

0.005 

0.7 

S.  A.  Lattimore 

Lake 

o  a 

Indianapolis,  Ind.,  well,               1880  
"     White  River,    "    

34-0 
29.0 

0.003 
0.005 

0.05 

0.2 

T.  C.  Van  Nuys 

*  Hofmann,  Dr.  Franz :     Die  Wasserversorgung  zu  Leipzig.     Pph.  8vo,  pp.  62. 
Leipzig,  1877. 


EXAMINATION   OF   GROUND   WATER.  12$ 

In  Table  XVII  are  given  the  results  of  the  partial  analyses 
of  some  ground-water  supplies,  together,  in  most  cases,  with  the 
analysis  of  the  neighboring  pond  or  stream.  The  chemical  ex- 
amination of  a  water  under  discussion  directs  itself,  mainly,  to 
proving  the  freedom  from  organic  matter  and  other  signs  of  pol- 
lution, and  to  ascertaining  that  the  hardness  is  not  excessive. 

In  this  connection  we  may  mention  a  peculiar  trouble  which 
has  occurred  at  several  foreign  water  works.* 

Since  September,  1877,  a  portion  of  the  Berlin  water  supply 
has  been  taken  from  the  neighborhood  of  the  "Tegeler  See/'  by 
means  of  a  series  or  line  of  23  wells  running  parallel  with  the 
shore  of  the  lake. 

Shortly  after  the  introduction  of  the  water,  complaints  arose 
as  to  its  quality,  and  investigation  proved  the  difficulty  to  be 
twofold.  It  is  frequently  noticed  that  water — and  especially 
water  from  a  driven  well — although  apparently  clear  when  first 
drawn,  becomes  turbid  on  standing  and  deposits  an  ochreous  sedi- 
ment. This  is  generally  due  to  the  presence  in  solution  of  the 
protocarbonate  or  to  some  organic  protosalt  of  iron,  which — on 
exposure  to  the  air — becomes  oxidized  and  changed  to  an  insoluble 
hydrated  sesquioxide.  This  was  the  cause  of  the  trouble  which 
occurred  at  Leipzig,  and  this  was  one  of  the  difficulties  with  the 
Tegel  ground  water,  but  the  microscope  showed  that  the  ochre- 
ous sediment  which  settled  from  samples  of  the  water,  and  which 
accumulated  in  the  reservoirs  and  in  the  pipes,  especially  in  "  dead 
ends,"  was  by  no  means  made  up  wholly  of  amorphous  mineral 
matter,  but  consisted  very  largely  of  alga,  dead  and  alive. 

Most  noticeable  among  the  alga  was  the  Crenothrix  Kuhni- 
ana  ( Crenothrix  polyspora,  Cohn).  This  plant  was  first  discovered 
by  Kiihn  in  1852,  in  the  drains  of  a  cultivated  field  in  Silesia,  but 
has  since  been  found  in  wells  in  various  parts  of  Europe,  and  is 
probably  very  widely  distributed. 

In  Berlin,  it  was  found  in  the  wells,  in  the  reservoirs  and  in 
the  service  pipes,  in  various  stages  of  development  and  decay. 
The  spores  are  minute  spherical  or  oblong  bodies  from  one  one- 
thousandth  to  six  one-thousandths  of  a  millimeter  in  diameter. 
From  these  spores,  and  by  other  means  of  development,  the 


*  This  is  abridged  from  an  account  of  the  trouble  given  by  the  author  in  the  Jour- 
nal of  the  Franklin  Institute,  March,  1882. 


126  WATER  SUPPLY. 

plants  grow  into  comparatively  long  threads,  each  of  which  on 
examination  is  seen  to  be  made  up  of  a  number  of  individual 
cells,  end  to  end,  inclosed  eventually  in  a  gelatinous  sheath.  The 
general  appearance  of  a  mass  of  these  threads  is  shown  in  the 
figure,  and  the  masses  are  sometimes  a  centimeter  or  more  in  di- 
ameter. 


FIG.  24. — CRENOTHRIX  KUHNIANA.    450  :  i. 

The  threads  are  at  first,  like  the  spores,  transparent  and 
colorless,  but  by  the  absorption  of  iron  in  some  form  or  other 
they  become  colored  from  olive-green  to  a  dark  brown.  They 
eventually,  in  many  cases,  become  incrusted  with  the  hydrate  of 
iron  to  such  an  extent  that  their  structure  becomes  invisible, 
but  it  may  be  made  evident  by  dissolving  away  the  hydrate  of 
iron  by  very  dilute  chlorhydric  acid.  Under  favorable  circum- 
stances the  plants  may  develop  with  great  rapidity,  and  Pro- 
fessor Kiihn  speaks  of  their  having  frequently  stopped  up  agricul- 
tural drain  pipes.  Also,  the  pipes  in  which  water  is  taken  from 
a  well  ten  meters  deep,  in  the  neighborhood  of  the  Plotzensee, 
near  Berlin,  have  in  summer  been  choked  and  nearly  filled  up  by 
the  multiplication  of  the  same  organisms.  In  the  reservoirs  and 
in  the  "  dead  ends  "  of  the  service  pipes  they  seemed  to  accumu- 


EXAMINATION  OF  GROUND  WATER. 

late  by  growth  as  well  as  by  deposition.  While  the  plants 
develop  more  rapidly  in  the  warm  season,  they  are  found  at  all 
times  of  the  year  in  all  stages  of  development. 

It  may  be  remarked,  in  this  connection,  that  the  Crenothrix 
has  great  vitality ;  thus,  Dr.  Zopf  exposed  a  quantity  in  water 
out-of-doors  from  the  first  of  January  to  the  middle  of  February. 
The  water  was,  of  course,  frozen,  and  during  the  time  the  tem- 
perature fell  as  low  as  to  — 8°R.  (ii°F.),  but  after  being  thawed 
out  the  plants  had,  in  a  few  weeks,  contrary  to  all  anticipation, 
revived  again  or  new  ones  had  grown  from  the  spores. 

The  Crenothrix  seems  to  live  and  develop  in  the  ground  itself, 
and  in  an  examination  which  was  made  of  the  water  from  a 
number  of  wells  in  different  parts  of  Berlin,  the  same  plant  was 
found  in  many  cases,  in  one  instance  at  a  depth  of  more  than  24 
meters  from  the  surface. 

Whether  its  presence  would  be  revealed  in  the  preliminary 
examination  of  a  ground  water  is  doubtful,  but  it  ought  certainly 
to  show  itself  if  pumping  experiments  were  carried  on  for  any 
considerable  length  of  time. 

There  seems  to  be  no  remedy  for  this  trouble.  It  was  found 
possible  in  Berlin  to  filter  the  water  artificially  through  sand — 
after  exposing  it  to  the  air — so  as  to  obtain  the  supply  perfectly 
clear ;  but,  of  course,  the  filters  were  very  much  fouled,  and,  on 
account  of  the  difficulty  of  washing  the  sand  thoroughly  and  the 
risk  that  the  spores  of  the  plant  would  eventually  find  their  way 
into  the  lower  part  of  the  filters  and  thence  into  the  service,  it 
was  thought  best  by  those  in  charge  of  the  works  to  abandon 
the  wells  altogether,  and  to  make  use  of  water  taken  directly 
from  the  lake  and  filtered  in  the  usual  manner.  The  same 
trouble  occurred  in  Halle,  and  it  is  stated  that  it  was  overcome 
by  sinking  other  wells  in  a  different  locality.  In  the  second 
locality  the  water  was  much  harder  and  free  from  the  Crenothrix  ; 
in  fact,  when  it  was  mixed  with  water  from  the  previous  source 
it  brought  about  the  extermination  of  the  plant ;  hence  it  has 
been  inferred  that  the  presence  of  a  considerable  amount  of  car- 
bonate of  lime  is  fatal  to  the  plant,  but  this  is  very  doubtful  in 
view  of  what  follows. 

The  same  trouble  has  occurred  recently  at  Lille,  in  France. 
The  source  of  supply  is  here  a  subterranean  reservoir  in  marl  and 
water-bearing  chalk  lying  near  the  surface.  The  water  comes  to 


128  WATER  SUPPLY. 

the  surface  in  actual  springs  which  originate  at  no  great  depth. 
The  hardness  of  the  water  is  about  25  Q  (French),  and  the  ex- 
amination made  in  1864  showed  44  parts  of  total  solids  in 
100,000,  a  large  proportion  being  carbonates  of  lime  and  mag- 
nesia. The  water  was  then  considered  of  good  quality,*  but  for 
some  time  there  has  been  complaint  of  a  red  color  and  of  an  un- 
pleasant taste  and  odor.  The  matter  becoming  very  serious  in 
the  spring  of  1882,  led  to  the  discovery  that  the  trouble  was 
mainly  due  to  the  Crenothrix.  The  previous  winter  had  been 
very  dry,  and  the  water  level  had  been  lowered  about  five  meters. 
The  rains  of  the  spring  raised  the  water  level,  and  seem  to  have 
washed  out  the  plants  into  the  sources  of  supply  ;  f  it  is  possible 
also  that  contamination  of  the  overlying  soil  had  increased  the 
amount  of  soluble  iron  salts  which  are  necessary  to  the  growth 
of  the  Crenothrix. 

The  Pollution   of  Domestic    Wells. 

In  isolated  dwellings  and  in  villages  and  small  towns  not  yet 
provided  with  a  public  water  supply,  drinking  water  must,  as  a 
rule,  be  obtained  either  by  collecting  the  rain  water  and  storing 
it  in  tanks  and  cisterns,  or  else  by  sinking  wells.  On  account  of 
the  clearness  and  nearly  uniform  temperature  of  the  ground  wa- 
ter, the  latter  method  is  usually  preferred  when  practicable.  In 
the  majority  of  cases  the  location  of  the  well  is  dictated  simply 
by  convenience,  and  it  frequently  happens  that  it  is  in  close  prox- 
imity to  a  privy,  or  to  cesspools,  or  to  a  barn  or  stable.  The  result 
is  that  the  well  is  very  liable  to  pollution,  and,  more  often  than 
not,  it  is  simply  a  question  of  time  when  the  water  shall  become 
unfit  for  use.  The  pollution  of  the  well  generally  takes  place 
gradually.  The  ground  gradually  becomes  charged  with  the 
soakage  from  the  privies  and  manure  heaps,  and  percolating  rain 
water  carries  the  impure  matter  into  the  ground  water  from 
which  the  well  draws  its  supply.  In  other  cases,  actual  channels 
are  formed,  by  which  the  foul  liquid  trickles  or  flows  into  the 
well  itself,  or  a  leaky  drain,  laid  near  the  well,  may  be  the  source 
of  the  trouble. 

Whatever  views  may  be  held  of  the  effect  upon  the  human 

*  Masquelez  :  Ville  de  Lille.  Etablissement  de  la  Distribution  d'Eau,  Paris,  1879. 
f  Alf.  Giard :  Comptes  rendus,  xcv  (1882),  247-249. 


POLLUTION   OF  WELLS.  129 

system  of  drinking  such  water,  there  is  no  question  whatever  as 
to  the  pollution  itself,  and  although  the  water  may  appear  clear 
and  bright,  and  be  inoffensive  to  the  senses,  chemical  examina- 
tion may  show  that  it  is  highly  charged  with  the  products  of  de- 
composition. Moreover,  there  are  hundreds  of  cases  on  record 
where  sickness  has  been  coincident  with  the  use  of  polluted  well 
water,  and,  although  the  evidence  is  of  necessity  circumstantial 
(see  Chapter  I),  it  is  too  striking  to  be  disregarded.  In  the 
present  state  of  knowledge,  it  must  be  said  that  the  continued 
use  of  a  well  water  proved  to  be  polluted  is  as  unjustifiable  as 
suicide  generally  is. 

It  is  often  difficult  to  persuade  the  owner  of  a  polluted  well 
to  abandon  its  use.  The  water  tastes  good  and  has  been  used 
for  years  without  producing  any  bad  effects.  Meanwhile,  how- 
ever, in  these  years  the  neighborhood  has  become  thickly  settled, 
the  various  possible  sources  of  contamination  have  increased, 
and  the  whole  ground  water  of  the  region  has  felt  the  effect.  At 
the  same  time,  in  urging  the  abandonment  of  the  well,  one  cannot 
say  that,  in  spite  of  the  pollution,  it  may  not  be  used  for  years 
more  without  noticeable  ill  effects.  Under  what  conditions  the 
water  may  become  injurious,  and  when,  no  one  can  say. 

It  is  also  difficult  to  realize  the  distance  from  which  the  pol- 
lution may  come.  Until  the  water  of  the  well  becomes  contam- 
inated to  a  very  great  extent,  the  taste  gives  no  evidence  of  con- 
tamination, but  occasionally  accidental  evidence  is  furnished  of 
the  distance  from  which  communication  with  the  well  may 
exist. 

An  illustration  of  this  point,  and  a  further  illustration  of 
certain  chemical  changes  which  have  been  already  alluded  to 
is  the  following.  In  Wernigerode,  Germany,'*  a  certain  well 
which  had  always  been  nearly  free  from  iron,  suddenly  began  to 
furnish  a  chalybeate  water.  Clear  when  drawn,  the  water  soon 
became  turbid,  and  deposited  on  standing  a  copious  ochrey  sedi- 
ment. It  was  finally  discovered  that  this  sudden  change  was  due 
to  the  emptying  of  several  casks  of  spoiled  beer  into  the  ground 
at  a  distance  of  some  35  meters  (115  feet).  The  organic  matter 
thus  introduced  into  the  ground  acted  as  a  reducing  agent  on 
the  ferric  oxide  contained  in  the  soil,  and  the  iron,  dissolved  as 

*  Wockowitz,  E.:  Wernigerode's  Trinkwasser.     Wernigerode,  1873. 
9 


130  WATER  SUPPLY. 

protocarbonate,  found  its  way  into  the  body  of  water  from  which 
the  well  was  supplied. 

In  some  places,  owing  to  the  very  nature  of  the  locality, 
shallow  wells  are  to  be  rejected  as  sources  of  supply.  Thus, 
Dr.  Smart  *  says,  with  reference  to  New  Orleans:  "  The  well 
waters  of  New  Orleans  are  unfit  for  use.  They  are  but  little 
less  impure  than  the  sewage  water  carried  off  by  the  drainage 
canals,  yet  they  are  reported  as  being  employed  for  family  use, 
in  bakeries,  and  for  stock,  especially  in  summer,  when  the  cistern 
supply  fails.  The  site  of  the  city  is  waterlogged  to  within  a 
few  feet  of  the  surface.  One  well,  on  Chestnut  street,  the  least 
impure  of  those  examined,  is  only  10  feet  deep,  and  contains  7 
feet  of  water.  The  saturated  soil  is  of  great  depth,  and  the 
ground  water  is  practically  stagnant.  The  filtration  into  the 
wells  is  insufficient  even  to  free  the  water  from  turbidity.  Or- 
ganic matter  is  unaffected  by  the  process.  The  water  contains 
alkaline  carbonates,  chlorides,  large  amounts  of  free  ammonia, 
but  no  nitrates  or  even  nitrites.  In  four  wells  examined,  the 
ammonia  from  organic  matter  amounted  to  0.039,  0.041,  0.044, 
0.080  part  ;  while  in  the  sewage  from  the  Orleans  canal  it  only 
reached  0.120  part.  These  samples  are  so  impure  that  the  use 
of  well  water  in  New  Orleans  should  be  interdicted.f  Even  care- 
ful filtration  should  not  be  relied  on  to  purify  such  waters.  Fil- 
tration is  not  a  process  by  which  dangerous  waters  may  be  util- 
ized, but  simply  a  guard  against  the  possibility  of  danger  in 
doubtful  waters." 

We  have  thus  far  spoken  only  of  wells  which  are  sunk  into 
the  ground  water.  These  are  the  most  common,  but  many  wells 
are  sunk  into  a  more  or  less  compact  rock,  and  the  water  comes 
through  fissures  in  the  rock.  In  such  cases  it  is  often  difficult  to 
tell  where  the  water  does  come  from,  and  the  well  is  liable  to 
contamination  from  distant  sources.  The  pollution  is  liable  to 
be  even  more  serious  than  in  wells  sunk  into  the  ground  water, 
because  the  contaminating  substances  carried  by  the  stream  of 
water  do  not  have  the  same  opportunity  to  be  oxidized  as  they 
do  when  the  water  passes  with  comparative  slowness  through  a 
body  of  sand  or  gravel. 

*  Bulletin  National  Board  of  Health,  April  17,  1880. 
t  Such  use  is  now  prohibited  by  law,  1883, 


EXAMINATION   OF  WELL  WATERS.  131 

Of  the  well  waters  which  are  submitted  to  chemical  examina- 
tion a  limited  number  show  by  the  absence  of  ammonia,  nitrog- 
eneous  organic  matter,  and  chlorides  in  appreciable  quantity, 
that  they  are  free  from  all  contamination  ;  on  the  other  hand,  a 
considerable  proportion  (not,  however,  one-half  according  to  the 
experience  of  the  author)  may  be  condemned  at  once  ;  the  re- 
mainder can  only  be  considered  doubtful  or  suspicious.  In  the 
cases  of  those  suspicious  wells  which  cannot  be  absolutely  con- 
demned, the  proper  course  is  to  have,  for  a  time  at  least,  some- 
what frequent  examinations  made  of  the  water  to  see  whether 
the  impurity  is  on  the  increase.  For  this  particular  purpose,  it 
is  usually  sufficient  to  follow  a  single  ingredient,  say,  for  exam- 
ple, the  chlorine  existing  as  chlorides.  If  the  amount  of  chlorine 
increases  to  any  considerable  extent,  the  source  of  impurity 
should  be  ascertained  and  the  water  be  protected  therefrom,  if 
possible,  or  else  be  rejected  from  use. 

It  may  be  said,  in  a  general  way,  that  a  good  well  water 
should  not  contain  over  0.005  Part  °f  ammonia  in  100,000,  or 
over  o.oio  part  "  albuminoid  ammonia,"  and,  in  most  places,  not 
over  i.o  part  of  chlorine  (as  chlorides).  The  amount  of  solid 
matter  in  solution  depends  necessarily  upon  the  locality,  and 
what  might  be  a  reasonable  amount  in  one  region  would  be  very 
abnormal  in  another.  The  presence  of  nitrates  is  also  suspicious, 
but,  unless  the  quantity  is  very  considerable,  cannot  alone  con- 
demn the  water.  Dr.  Charles  Smart,  U.  S.  A.,  accepts  o.oio 
albuminoid  ammonia  in  100,000  as  suspicious,  and  0.015  as  a  limit 
in  the  case  of  well  waters  "  in  the  denser  settlements,  and  in  every 
case  where  an  animal  origin  to  the  organic  matter  is  indicated  by 
careful  survey  or  chemical  analysis." 

In  the  case  of  doubtful  waters,  the  greatest  satisfaction  may 
be  obtained  when  it  is  possible  to  find  in  the  same  immediate 
neighborhood  a  well  of  whose  freedom  from  contamination  there 
can  be  no  doubt.  The  comparison  of  the  waters  of  the  two 
wells  will  probably  enable  one  to  decide  the  question  as  to  the 
contamination  of  the  first  well.  The  next  most  satisfactory 
course  of  procedure  is  to  throw  a  quantity  of  salt  (or  brine)  into 
the  various  cesspools,  drains,  etc.,  and  to  determine  at  frequent 
intervals  the  amount  of  chlorine  (as  chlorides)  in  the  water  of 
the  well.  As  instances  in  which  this  method  was  used  with  good 
results,  the  two  following  may  suffice : 


132 


WATER   SUPPLY. 


In  No.  I,  the  well  was  located  100  feet  from  the  privy  ;  a 
bushel  of  coarse  salt  was  put  into  the  privy-vault  October  24,  and 
a  bushel  of  fine  salt  on  October  31.  This  caused  an  evident 
increase  of  the  amount  of  chlorides  in  the  well,  as  appears  from 
the  figures.  In  case  No.  II,  two  bushels  of  salt  were  put  into  a 
cesspool  which  was  75  feet  from  the  well.  A  sample  of  water 
was  then  taken  and  afterward  at  intervals  of  three  days.  The 
effect  on  the  well  water  was  not  as  marked  as  in  No.  I,  but 
the  results  were  confirmed  by  a  subsequent  examination  of  the 
locality : 


Date  of  Examination. 

Chlorine,  expressed 
as  Parts  in  100,000. 

October  17 

3-3 

26 

3-9 

29 

3-9 

November    2 

4.0 

5 

4-4 

8 

3-5 

13 

3-4 

17 

3-4 

20 

3-3 

23 

3-1 

II.                      II. 

No.  of  Sample.                 Chlorine. 

I 

•4 

J 

•5 
.6 

4 

•7 

6 

•  7 
•9 

7                           2.6 

8                                    2.0 

9                           2.0 
10                           1.9 

In  Table  XXIII  are  brought  together  the  results  of  the 
examination  of  a  few  well  waters  from  various  localities.  The 
table  might  be  extended  to  an  indefinite  length,  as  the  reports 
of  boards  of  health  and  water  committees  would,  in  almost 
every  case,  contribute  to  the  list. 

TABLE  XVIII. — EXAMINATION   OF  WELL  WATER. 
[Results  expressed  in  Parts  in  100,000.] 


LOCALITY. 

TOTAL  SOLIDS. 

AMMONIA. 

u  ALBUMINOID 
AMMONIA." 

CHLORINE. 

QUALITY. 

AUTHORITY. 

Saugus  Mass        .           .   . 

7-3 

21.0 
19-3 
63.1 
112.  1 

3T-7 
68.6 

37-4 

£1 

45-0 

O.OOI 
0.002 
O.OO2 
O.OO6 
0.005 
0.014 
0.230 
0.002 
0 
O.OOI 
0.006 

0.002 
0.002 

0.009 
0.015 
0.013 
0.009 
0.029 
0.005 

0 

0.007 
0.018 

i.i 
3  « 

i-7 

10.2 
40.0 
2.2 
9-5 

9-3 
0.8 
8.9 
4.0 

Good. 
Suspicious 

Polluted. 

Good. 

Doubtful. 
Bad. 

W.  R.  Nichols. 
E.  Waller. 

Another. 

Williamstown,  Mass  

Another    

"            Another  
North  Adams  Mass        .... 

Gloucester  Mass 

Watertown    N  Y 

Croton  Falls,  N.  Y  

Lockport,  NY        

Southampton  L    I 

CHAPTER   VII. 

DEEP   SEATED   WATER  AS   A   SOURCE   OF   SUPPLY. 

WHILE  a  portion  of  the  rainfall  which  soaks  into  the  ground 
soon  encounters  an  impervious  stratum,  above  which  it  collects 
to  form  the  ground  water  of  the  locality,  much  of  the  water  pre- 
cipitated from  the  atmosphere  falls  upon  the  edges  of  upturned 
rocky  strata,  or  upon  rock  deposits  which  are  either  themselves 
porous  or  so  fissured  that  they  afford  a  more  or  less  free  passage 
for  water.  When  the  pervious  stratum  has  an  outcrop  at  some 
lower  level,  the  water  may  issue  in  the  form  of  springs,  more  or 
less  copious.  Where  the  course  of  the  water  has  not  been  too  long, 
and  it  has  not,  consequently,  taken  up  a  large  amount  of  mineral 
matter,  such  springs  furnish  one  of  the  best  sources  of  drinking 
water,  although  the  water  is  very  often,  in  fact  usually,  less  well- 
suited  for  technical  purposes,  on  account  of  its  hardness.  The 
advantage  of  spring  water  over  surface  water  for  drinking  is  con- 
sidered by  some  so  great  as  to  justify  the  incurring  of  very  con- 
siderable expense  in  order  to  procure  it.  Thus,  the  city  of  Vienna 
constructed  extensive  water  works  for  the  sake  of  bringing  water 
from  springs  which  are  sixty  miles  distant. 

Artesian  Wells. 

When  the  water  precipitated  from  the  atmosphere  is  absorbed 
by  a  pervious  stratum  which  is  situated  between  two  impervious 
strata,  the  water  may  exist  under  considerable  hydrostatic  press- 
ure. The  occurrence  of  a  "  fault  "  in  the  strata  may  allow  the 
water  to  rise  to  the  surface  of  the  ground  as  springs,  but  often 
the  water  can  be  utilized  only  by  sinking  or  boring  artesian  wells. 

An  artesian  well  is  a  well  which  is  sunk  or  bored  through  an 
impervious  stratum  so  as  to  reach  a  water-bearing  stratum  in 
which  the  water  is  under  hydrostatic  pressure ;  so  that,  as  soon 
as  the  well  is  opened,  it  rises  through  the  impervious  stratum 
and  often  to,  or  higher  than,  the  surface  of  the  ground.  Arte- 


134  WATER  SUPPLY. 

sian  wells  may,  therefore,  be  regarded  as  artificially  opened  springs. 
The  term  artesian  is  frequently  applied  to  non-flowing  deep  wells, 
but,  while  the  question  of  flowing  or  non-flowing  may  be  unes- 
sential, the  term  is  improperly  applied  to  wells,  however  deep, 

when  the  water  is  taken  from  the 
deposit  into  which  the  well  is 
bored  or  sunk,  and  where  the 
water  collects  from  the  fissures 
and  cavities  of  the  rock  itself. 
Thus,  in  England,  there  are  many 
deep  wells  in  the  chalk  or  in  the 
new  red  sandstone  which  collect 

FlG.  25.— ARTESIAN  WELL. 

and  utilize  water  from  the  chalk 

or  from  the  sandstone  itself,  and  which  are  not  properly  to  be  char- 
acterized as  artesian.  In  this  country,  driven  wells  are  often  called 
artesian  wells,  and  they  may  be  properly  so  designated  if  they  pass 
through  a  stratum  of  clay,  so  that  the  water  rises  from  an  underly- 
ing deposit  not  in  communication  with  the  ground  or  surface  water 
of  the  same  locality  :  driven  wells,  however,  as  we  have  already 
seen,  often  utilize  simply  the  ground  water  where  they  are  driven. 

Although,  within  modern  times,  improvements  have  been 
made  in  the  methods  and  apparatus  employed  for  boring  wells, 
wells  of  this  description  are  of  great  antiquity.  They  are  found 
in  China,  and  many  such  wells  have  existed  for  a  long  time  in 
North  Africa,  in  the  oases  of  the  Sahara.  Here,  until  recently, 
they  were  excavated  by  hand,  the  earth  and  other  material  being 
drawn  up  in  baskets.  Finally,  a  thin  stratum  of  rock  was  reached 
beneath  which  experience  had  shown  that  water  existed.  This 
rock  stratum  was  cautiously  perforated,  and  as  soon  as  it  was 
pierced  the  workman  was  drawn  up  rapidly — and  not  always 
safely — as  he  was  sometimes  overtaken  by  the  rush  of  water. 
The  French  in  the  province  of  Constantine  (Algeria),  between 
the  years  1856  and  1878,  bored  over  400  wells.  The  flowing  wells 
numbered  158,  with  an  average  depth  of  85.5  meters;  the  tem- 
perature of  the  water  was  generally  betwen  21°  C.  and  26°  C.,  and 
the  total  solids  between  300  and  600  parts  in  100,000* 

There  are  a  great  many  artesian  wells  in  various  parts  of  the 

*  Les  Forages  artesiens  de  la  province  de  Constantine  (Algerie).  Resume  des 
Travaux  executes  de  1856  a  1878.  Par  M.  Jus.  8vo,  pp.  97.  Paris,  Imprimerie 
Nationale,  1878. 


ARTESIAN  WELLS.  135 

United  States.  Thus,  Professor  Winchell,  in  1856,*  mentions  as 
many  as  74  such  wells  in  a  single  and  somewhat  circumscribed 
region  of  middle  Alabama,  and,  of  late  years,  many  wells  have 
been  sunk  in  the  southwestern  part  of  the  country  with  favora- 
ble results. 

The  sinking  of  artesian  wells  is  attended  with  great  uncer- 
tainty as  regards  both  the  quality  and  the  quantity  of  the  water 
to  be  obtained,  and  many  wells  have  been  sunk  which  have  failed 
to  reach  water  at  all,  or  from  which  only  water  unfit  for  any  do- 
mestic use  has  been  obtainable.  To  judge  of  the  probability  of 
success  in  sinking  a  well  in  a  new  locality,  a  knowledge  of  the 
geological  character  of  the  underlying  strata  is  essential.  At 
Charleston,  S.  C.,  where  are  several  successful  artesian  wells,  f  the 
possibility  of  obtaining  such  wells  was  inferred  from  a  knowledge 
of  the  geology  of  the  region.  More  than  100  miles  from  the  city, 
starting  from  Augusta,  Ga.,  and  proceeding  northeastwardly,  a 
granite  ridge  rises  to  the  surface  of  the  earth,  exposed  to  view  in 
favorable  positions,  elsewhere  covered  with  superficial  drift  sands 
and  clays.  The  line  may  be  followed  northward  through  North 
Carolina,  Virginia,  and  Maryland.  On  the  broad  surface  of  this 
granite  ridge,  and  on  its  seaward  slope,  the  sands  drink  in  the 
rain  water  that  falls.  The  streams  from  the  up  country  that 
cross  the  ridge  may  also  supply  their  quota.  The  water  thus 
imbibed  sinks  down  by  the  force  of  gravity,  ever  seeking  the  low- 
est attainable  position.  Now,  the  tertiary  beds  of  the  Charles- 
ton Basin,  the  cretaceous  beds  under  them,  and  any  other  sedi- 
mentary beds  beneath  the  cretaceous,  must  rest  against  this 
eastern  slope  of  the  granite  ridge,  and  their  sandy  layers  must 
drink  in  the  water  filtering  through  the  sands.  As  all  of  these  beds 
have  a  gentle  slope  toward  the  coast,  the  water  will  follow  them 
down  in  their  course.  These  formations,  no  doubt,  continue 
their  course  under  water  for  many  miles,  and,  indeed,  there  is 
evidence  that  the  water  contained  in  them  finds  a  discharge  into 
the  sea.  To  this  cause  are  attributed  the  springs  of  fresh  water 
that  have  been  observed  to  rise,  bubbling  up  at  times  in  notable 
quantity  through  the  salt  water  at  points  along  the  coast,  fifteen  or 
twenty  miles  from  the  shore.  Moreover,  in  all  the  deep  wells  in 

*  Proc.  Amer.  Assoc.,  x  (1857),  p.  83. 

f  Municipal  Report  of  the  City  of  Charleston,  S.  C.     Artesian  Wells,  1881. 


136  WATER   SUPPLY. 

Charleston,  varying  from  60  to  1,260  feet  in  depth,  the  level  or 
head  of  water  in  the  pipes  has  been  observed  to  oscillate  at  tidal 
intervals  to  an  extent  varying  from  4  to  6  inches.  The  explana- 
tion is  simple.  In  issuing  from  its  natural  vent  under  the  sea 
the  fresh  water  must  lift  the  column  of  salt  water  above,  the 
weight  of  which  acts  as  an  obstruction.  When  the  tide  at  sea 
is  high,  this  column  is  greater  than  it  was  at  low  tide.  The  con- 
sequence is  a  diminution  of  the  escape  of  water  by  that  channel, 
and  a  compensating  increase  of  the  discharge  through  other 
channels  not  so  obstructed,  and  an  increase  in  the  head  of  water 
in  the  wells.* 

One  disadvantage  of  sinking  artesian  wells  for  town  supply 
is  the  great  uncertainty  as  to  the  quality  of  the  water,  and 
the  fact  that  water  from  considerable  depths  is  often  of  ele- 
vated temperature,  and  therefore  not  fit  to  drink  unless  cooled. 
Moreover,  the  water  is  apt  to  be  charged  with  a  large  amount 
of  mineral  matter  derived  from  the  strata  through  which  it  has 
flowed  or  percolated,  or  in  contact  with  which  it  has  remained 
for  a  long  period  of  time.  The  widely-known  well  at  Cre- 
nelle, Paris,  which  is  about  1,800  feet  deep,  has  a  temperature  of 
27°  C.  (8o°.6  F.),  and  contains  only  about  14  parts  in  100,000  of 
dissolved  solids,  whereas  a  well  in  St.  Louis,  Missouri,  sunk  at 
the  sugar  refinery  of  Belcher  and  Brothers  to  a  depth  of  over 
2,000  feet,  and  at  an  expense  of  $10,000,  furnishes  about  75  gal- 
lons per  minute  of  water  emitting  a  strong  odor  of  sulphuretted 
hydrogen,  and  containing  879.1  parts  of  dissolved  matter  in 
100,000  parts ;  this  water  is  entirely  useless  for  the  purposes  of 
the  refinery  or  for  domestic  use.  As  already  stated,  the  artesian 
wells  in  Algeria  contain  from  300  to  600  parts  of  dissolved 
solids  in  100,000  parts  of  water,  and  would,  in  most  localities,  be 
at  once  rejected  even  for  purposes  of  irrigation.  In  the  absence, 
however,  of  better  water,  such  wells  as  these  are  regarded  as 
godsends  by  the  inhabitants. 

The  fact  of  a  considerable  amount  of  dissolved  solids  does 
not  necessarily  prove  that  an  artesian  water  is  unfit  for  use, 
although  usually  the  salts  present  are  objectionable  in  character. 
Sometimes  the  dissolved  matter,  in  the  absence  of  lime,  magne- 

*  The  above    statement    is   condensed  from  the  Charleston  Municipal   Report 
already  cited. 


ARTESIAN  WELLS.  137 

sia  and  sulphates,  may  be  unobjectionable  in  character,  although 
the  large  amount  present  may  be  undesirable.  For  example,  the 
water  of  the  Wentworth  Street  artesian  well  in  Charleston,  S.  C., 
which  contains  273.66  parts  of  total  solids  in  100,000,  has  been 
used  for  years.  In  this  case  the  dissolved  matter  is  almost 
entirely  common  salt  and  carbonate  of  soda,  and  the  use  of  the 
water  is  held  to  be  beneficial  in  dyspepsia  and  kindred  diseases. 
The  water  of  the  more  recent  Citadel  Green  well  contains 
only  111.55  parts  in  100,000  of  solid  matter,  likewise  consisting 
mainly  of  these  two  salts.  The  water  is  considered  wholesome 
as  a  drink,  and,  for  washing,  the  presence  of  the  carbonate  of 
soda  makes  it  an  excellent  water ;  the  principal  objection  found 
to  it  is  that  the  carbonate  of  soda  gives  to  rice,  hominy  and 
other  farinaceous  articles  cooked  in  it  a  light  golden  tinge,  owing 
to  the  action  of  the  carbonate  of  soda  on  the  starch  in  such  arti- 
cles. In  the  laundry,  also,  it  cannot  be  used  in  the  mixing  of  the 
starch  for  the  same  reason. 

It  may  be  here  noted  that  the  quantity  of  water  obtained  from 
an  artesian  well  is  often  seriously  diminished  by  the  sinking  of 
other  wells  into  the  same  water-bearing  stratum.  This  has  been 
the  experience  in  many  localities.  With  reference  to  wells  in  the 
neighborhood  of  London,  Eng.,  De  Ranee  says : 

"  The  outcrop  of  the  lower  London  tertiaries  is  about  100 
feet  above  the  Thames,  whilst  their  depth  below  it  varies  from 
200  to  300  feet,  the  only  notch  in  the  rim  of  the  basin  being 
the  valley  of  the  Thames  at  Deptford  and  Greenwich,  where 
the  outcrop  is  100  feet  lower  than  the  remainder  of  the  margin 
of  the  basin ;  the  sectional  area  of  the  depressed  portion  being 
much  less  than  the  elevated  portion,  far  less  water  can  escape 
than  can  be  absorbed  by  the  sands,  which  are  practically  water- 
logged by  the  overlying,  impermeable  clay,  through  which  borings 
were  carried  to  a  depth  of  80  to  140  feet  at  the  beginning  of  the 
century;  at  that  time  the  liberated  water  flowed  up  the  bore- 
holes, and  rose  permanently  above  the  level  of  the  Thames  until 
the  supply  was  over-pumped,  and  it  has  fallen  to  70  feet  below 
Trinity  high-water  mark.  To  supply  the  deficiency,  most  of  the 
artesian  wells  in  London  have  been  carried  down  to  the  chalk 
beneath,  to  intercept  the  water  which  circulates  freely  in  the  fis- 
sures and  lines  of  joints.  The  level  to  which  water  will  rise  is 
steadily  decreasing." 


138  WATER  SUPPLY. 

Deep   Wells, 

In  certain  geological  formations,  the  nature  of  which  does  not 
admit  of  the  construction  of  artesian  wells  proper,  water  may 
often  be  obtained  in  large  quantities  by  sinking  shafts,  in  which 
the  water  collects  and  from  which  it  may  be  raised  to  the  surface 
by  pumps.  Horizontal  tunnels  may  be  carried  from  the  shaft,  at 
one  or  more  levels,  so  as  to  intercept  the  water  flowing  through 
the  fissures  or  along  the  planes  of  stratification.  Sometimes,  in- 
deed, the  water  may  be  obtained  solely  by  means  of  a  horizontal 
tunnel,  the  opening  being  made  in  the  face  of  a  bluff.  Thus, 
Dubuque,  Iowa,  is  supplied  from  a  tunnel  or  adit  penetrating  the 
bluffs  and  extending  for  about  a  mile  in  length  at  a  depth,  from 
the  surface  of  the  ground,  of  from  100  to  200  feet. 

Deep  wells  are  used  as  sources  of  public  supply,  to  some 
extent,  but  the  greater  number  the  world  over  are  sunk  or  bored 
for  private  establishments,  notably  for  breweries.  It  is  stated 
that  in  the  city  of  New  York  there  are  as  many  as  40  wells 
on  Manhattan  Island,  although  some  of  them  are  not  now  in  use. 
Nearly  one-half  this  number  are  owned  by  breweries.  The  wells 
vary  in  depth  from  26  to  2,000  feet.  Eighteen  are  500  feet  or 
more  in  depth.  The  diameter  also  varies,  being  from  2\  to  10 
inches,  although  the  majority  are  6  or  6^  inches.  The  capacity 
of  the  wells  ranges  from  2,000  gallons  to  126,000  gallons  in  24 
hours ;  and  the  temperature  of  the  water,  so  far  as  noted,  is 
between  50°  and  59°  F.  As  might  be  expected  from  the  geolog- 
ical formation  of  the  island,  the  wells  are,  in  most  cases,  bored 
in  gneiss  and  mica  schist.* 

In  England,  where  deep  wells  are  used  to  a  considerable  ex- 
tent as  sources  of  town  supply,  the  water-bearing  capacity  of  the 
various  geological  formations,  and  the  character  of  the  water  to 
be  obtained  therefrom,  has  probably  been  studied  more  carefully 
than  elsewhere. f  Of  the  water  supply  of  Liverpool,  5,500,000 
(imperial)  gallons  are  daily  pumped  from  the  wells  in  the  new  red 
sandstone,  and  London  receives  daily  some  8,000,000  (imperial) 
gallons  from  deep  wells  in  the  chalk. 

*  Sanitary  Engineer,  October  12,  1882. 

f  See  Sixth  Report  of  Rivers  Pollution  Commission  ;  also,  the  various  (annual) 
reports  of  the  Underground  Water  Committee  of  the  British  Association  ;  also,  De 
Ranee,  Water  Supply  of  England  and  Wales. 


DEEP  WELLS.  139 

Fig.  26  shows  a  well  which  is  sunk  in  the  new  red  sandstone, 
at  Whiston,  England.*  Two  wells,  each  9  feet  in  diameter  and  12 
feet  apart,  were  sunk  to  a  depth  of  135  feet  and  then  continued 
to  a  depth  of  225  feet  as  a  single  well,  30  feet  long  and  9  feet 
broad.  The  bottom  of  the  well  is  25  feet  below  mean  sea  level, 
and  when  first  sunk,  supplied  some  400,000  gallons  in  24  hours, 
with  a  depth  of  about  9  feet  of  water  in  the  well.  The  manner 
in  which  the  well  cuts  the  strata  of  the  sandstone  is  evident  from 
the  figure,  the  water  having  a  natural  tendency  to  flow  along  the 
planes  of  stratification  toward  the  fault  shown  at  the  left,  which 
presents  a  barrier  to  its  farther  progress.  The  works  were  sub- 
sequently extended  by  sinking  and  boring  the  auxiliary  well  in 
the  right  of  the  figure,  and  connecting  the  two  wells  by  means 
of  a  tunnel.  The  supply  obtained  from  the  combined  wells,  was, 
in  1876,  about  900,000  (imperial)  gallons  in  24  hours. 

The  capacity  of  a  rock  for  storing  and  absorbing  water  varies 
with  its  texture  and  character ;  and  when,  after  long  continued 
rains,  the  rock  has  become  fully  saturated,  no  more  water  can  be 
absorbed,  and  all  additional  supplies  pass  off  as  floods,  as  abso- 
lutely as  if  the  precipitation  took  place  on  an  impermeable  for- 
mation. Many  rocks  thus  contain,  in  their  natural  and  undis- 
turbed condition,  water  which  was  derived  from  the  atmosphere 
long  ago,  and  in  some  cases  the  rocks  may  contain  saline  solutions 
which  have  filled  their  pores  from  the  time  of  their  formation.f 
When  a  well  is  sunk  into  such  a  deposit,  the  water  may  be  grad- 
ually forced  out  by  the  pressure  of  the  water  accumulated  in 
other  parts  of  the  same  stratum,  or  in  communicating  strata,  but 
it  may  take  a  very  long  time  to  exhaust  the  subterranean  reser- 
voir. In  some  cases,  near  the  sea,  there  may  be  communication 
with  the  ocean,  which  may  thus  produce  the  hydrostatic  pressure, 
but  which  may  not  contribute  by  its  waters  directly,  or  at  least 
not  for  a  long  time  after  the  well  is  opened.  Some  deep  wells 
near  the  sea  gradually  become  more  brackish,  probably  from  the 
fact  that  the  purer  water  which  originally  filled  the  pores  of  the 
rocks,  and  perhaps  subterranean  reservoirs,  is  gradually  exhausted, 
and  other  water — in  this  case  sea  water — comes  in  to  replace  it. 

Some  idea  of  the  vast  amount  of  water  stored  below  the  sur 

*  Proc.  Inst.  Civ.  Eng.  Gr.  Britain,  xlix  (1877),  p.  221. 

f  See  Hunt's  Chemical  and  Geological  Essays,  p.  104  and  elsewhere. 


DEEP   WELLS.  14! 

face  of  the  ground  may  be  obtained  from  the  following  extract 
(De  Ranee)  : 

"  In  the  Thames  and  east  coast  district  are  not  less  than  4,000 
square  miles  of  pervious  cretaceous  rocks,  receiving  not  less  than 
5  inches  of  rain  annually,  or  a  daily  absorption  of  800,000,000 
gallons.  It  is  readily  understood  with  these  figures,  how  the  dry 
weather  flow  of  the  Thames  is  kept  up  by  chalk  springs ;  one- 
fifth  of  the  yield  is  sufficient  for  4,000,000  people,  and  taking  the 
oolite  supply,  the  total  volume  of  water  absorbed  by  underground 
sources  in  the  Thames  and  east  coast  river  basins  may  be  taken  as 
1,125,000,000  gallons — a  supply  equal  to  the  wants  of  22,000,000 
people,  or  nearly  that  of  the  total  inhabitants  of  England,  sup- 
posing that  the  whole  of  the  5  inches  of  rainfall  absorbed  could 
be  pumped  up." 

It  is,  of  course,  impossible  to  utilize  all  the  water  actually 
contained  in  any  rock.  From  a  compact  rock  like  chalk  or  lime- 
stone, a  portion  of  the  water  is  furnished  by  cracks  and  fissures, 
and  this  is  readily  given  up  ;  another  portion  passes  through  the 
rock  itself,  and  although  the  water  may  be  received  and  absorbed 
with  great  rapidity,  it  is  delivered  with  extreme  slowness,  and  a 
struggle  is  maintained,  as  it  were,  between  capillarity  and  gravity. 

Baldwin  Latham  *  has  called  attention  to  the  influence  of  the 
barometric  pressure  on  the  volume  of  water  discharged  by  springs 
(or  yielded  by  deep  wells).  When  the  barometer  falls,  the  air 
confined  in  the  fissures  of  the  rocks  tends  to  expand  and  force  out 
the  water,  and  the  volume  of  the  springs  increases ;  when  there 
is  a  rise  in  the  barometer,  there  is  a  diminution  of  the  flow.  A 
more  or  less  marked  coincidence  between  barometric  changes 
and  variations  in  the  amount  of  water  discharged  by  mineral 
springs  was  noticed  long  ago,  and  various  explanations  have 
been  offered  to  account  for  the  phenomenon. f 

When  a  well  is  opened  in  a  water-bearing  rock,  the  level  of 
the  water,  or  plane  of  saturation,  will  be  found  to  vary  within 
certain  limits,  being  governed  by  the  amount  of  rainfall  absorbed. 
This  level,  after  extensive  pumping,  is  artificially  and  locally 
lowered,  but,  on  the  cessation  of  pumping,  the  original  level  is 
restored  by  a  sufficient  interval  of  rest,  provided  the  volume 

*  Nature,  September,  1881. 

f  See,  for  example,  Alois  Nowak  :  Ueber  die  barometrischen  Ergiebigkeits- 
Schwankungen  der  Quellen  in  Allgemeinem.  Prag,  1880. 


142  WATER  SUPPLY. 

abstracted  annually  is  not  more  than  is  supplied  by  the  rainfall. 
If  the  demand  upon  a  deep  well  is  greater  than  the  supply  re- 
ceived directly  or  indirectly  from  the  rainfall,  the  well  will  show 
signs  of  exhaustion ;  the  supply  may,  however,  be  kept  up  by 
deepening  the  well,  that  is,  by  taking  the  water  from  a  lower 
level.  Many  wells  gradually  furnish  less  and  less  water,  because 
in  the  beginning  there  was  a  quantity  of  water  stored  in  the  rock, 
which  has  gradually  become  exhausted.  On  the  other  hand, 
some  wells  furnish  a  supply  increasing  in  abundance,  owing  to 
the  fact  that  the  passages  through  which  the  water  comes  become 
less  obstructed  and  of  larger  size.  Thus,  according  to  the  Rivers 
Pollution  Commission,  every  1,000,000  (imp.)  gallons  of  water 
drawn  from  the  chalk  carries  with  it,  in  solution,  on  an  average 
ij  tons  of  chalk  through  which  it  has  percolated,  causing  an  ad- 
ditional storage  room  for  no  gallons  of  water;  so  that  the  yield 
of  a  well  draining  a  given  area  in  the  chalk,  other  things  being 
equal,  ought  to  gradually  increase  until  the  maximum  limit  of 
permeability  is  reached.  As  a  further  example  of  the  same 
'thing,  it  may  be  mentioned  that,  during  the  construction  of  the 
tunnel  at  the  Whiston.  water  works,  upward  of  350  tons  of  sand 
were  in  a  few  years  washed  from  the  fissures  of  the  rocks,  thus 
increasing  the  storage  capacity  of  the  rock. 

Characteristics  and  Examination  of  Deep-seated  Water. 

The  questions  of  the  amount  of  water  to  be  obtained  from 
springs  and  deep  wells,  and  of  the  probability  of  procuring  water 
by  means  of  artesian  wells  in  any  given  locality  are  questions  for 
the  engineer  and  geologist.  The  fact  that  all  such  waters  are 
liable  to  contain  an  excess  of  mineral  matter  has  been  sufficiently 
noticed :  the  chemical  examination  concerns  itself  mainly  with 
the  amount  and  nature  of  the  dissolved  salts.  These  deep 
waters  are  characterized,  in  general,  by  an  absence  of  organic 
matter,  but  that  even  deep  wells  are  liable  to  pollution  may  be 
easily  realized  by  an  inspection  of  Figure  26.  It  is  very  evident 
that  any  polluting  matters  in  the  soil  might  easily  find  their  way 
into  the  well,  being  carried  downward  by  the  water  passing 
along  the  planes  of  stratification.  In  the  case  of  the  water  works 
at  Whiston,  all  the  wells  in  the  immediate  neighborhood  were 
affected,  most  of  them  losing  their  water  altogether.  This  in- 


DEEP   WELLS.  143 

fluence  was  felt  at  least  i-J  miles  to  the  southeast  and  more  than 
a  mile  to  the  south.  Where  the  water  flows  underground 
through  cracks  and  fissures  the  polluting  substances  do  not  have 
the  opportunity  to  become  oxidized  and  harmless,  as  when  the 
water  passes  slowly  through  a  gravel  deposit.  Mr.  Baldwin 
Latham  has  connected  the  periodic  outbreaks  of  fever  in  the 
parish  of  Croydon,  England,  with  the  intermittent  appearance 
of  springs  called  the  Bourne.  The  water  which  is  reabsorbed  by 
the  chalk  lower  down,  is  supposed  to  carry  the  objectionable 
substances  to  the  wells  in  the  center  of  the  old  town.  When 
the  springs  are  low  and  the  Bourne  begins  to  run,  after  a  sudden 
and  copious  rainfall,  the  water  line  under  the  town  is  elevated 
and  an  outbreak  of  enteric  fever  results.  Even  with  artesian 
wells  there  is  not  perfect  security,  for  many  such  wells — espe 
cially  when  first  opened — throw  out  fragments  of  vegetable  sub- 
stances, and  even  living  fish  and  other  small  aquatic  animals, 
showing  that  they  must  have  a  more  or  less  direct  communica- 
tion with  the  surface. 

Signs  of  pollution  in  such  waters  must  be  sought  mainly  in 
the  "  organic  matter "  as  variously  determined  :  chlorides  are 
often  present  in  considerable  amount,  but  are  not  evidence  of 
impurity ;  nitrogen  in  the  form  of  nitrites  and  nitrates  is  also 
often  present  in  notable  quantity  in  water  of  deep  wells,  espe- 
cially in  the  chalk,  and  is  no  sign  of  contamination ;  ammonia 
may  also  be  allowed  in  amounts  which  would  be  suspicious  in 
shallow  wells. 

While  the  artesian  wells  often  furnish  water  the  temperature 
of  which  is  objectionably  high,  the  water  of  many  springs  and  of 
ordinary  deep  wells  is  usually  of  nearly  uniform  and  of  compar- 
atively low  temperature.  In  fact,  the  sinking  of  deep  wells  in 
connection  with  breweries  is  partly  due  to  the  fancied  necessity 
for  hard  water  in  brewing  certain  kinds  of  beer,  and  partly  to 
furnish  an  abundance  of  cold  water  for  cooling  purposes. 

It  is  a  curious  fact  that  the  hard  water  from  springs  and  deep 
wells,  though  clear  and  bright  when  first  obtained,  becomes 
covered  with  a  confervoid  growth  when  exposed  to  the  sunlight 
in  open  reservoirs,  and  the  tubes  of  some  artesian  wells  become 
lined  with  a  growth  of  algae.  If  it  is  necessary  to  store  the 
water  from  deep  wells,  this  should  be  done  in  covered  reservoirs  ; 
this  is,  of  course,  desirable  also  as  a  means  of  avoiding  elevation 


144 


WATER   SUPPLY. 


of  temperature  in  summer  if  the  water  remains  in  the  reservoir 
for  any  considerable  time. 

Table  XIX  contains  some  details  with  reference  to  artesian 
TABLE  XIX.— EXAMINATION  OF  ARTESIAN  AND  DEEP  WELLS. 


LOCALITY. 

2 

W 
P 

TEMPERATURE  IN 
CENTIGRADE 
DEGREES. 

HARDNESS  : 
PARTS  IN 
100,000. 

TOTAL  SOLIDS  : 
PARTS  IN 

100,000. 

AUTHORITY. 

Artesian  Wells. 
Crenelle    Paris               

1,  806 

27 

14.2 

Peligot,  1857. 

28 

14.  i 

Poggiale  &  Lambert,  1862. 

1878   7 

J   M   Merrick 

Chicago  111 

14 

Louisville,  Ky.  ,  Dupont's  Well  

2,o86 

24.5 

1570.0 

J.  Lawrence  Smith. 

St  Louis  Mo                  .         

23 

879.1 

A    Litton,  M  D 

"         Mo.,  Asylum  Well  

0.843 

40.5 

C.  C.  Broadhead. 

Charleston,  S.  C.,  Wentworth  Street 
u               "       Citadel  Green.... 
"       ChisholmMill.... 
Coosaw  S   C                   

I,2OO 
1,970 

425 
760 

30-7 

37  5 

273-7 
in.  6 

369-7 
82.7 

C.  U.  Shepard,  Jr. 
S.  T.  Robinson,  Jr. 
Wm.  Robertson. 
F    F.  Chisholm. 

Deep  Wells. 

Rivers  Pollution  Com. 

Birmingham,  Eng  
"            Another           

300 

10    2 

10  8 

.11 

15  i 

31.3 

Bradford  Eng  

^60 

12    8 

14  i 

55-4 

u 

Brighton    Eng                           

I     285 

Q    9 

35-4 

11 

Liverpool  ,  Bootle  Well  

3T2 

10  4 

126 

^4-4 

M 

London,  Trafalgar  Square  
Jersey  City,  N.  J.,  Secaucus  Works. 
Newark,  N.  J.,  Celluloid  Works.  .  .  . 
"        Lister  Bros  
Paterson,  N.  J.,  Burton  Brewing  Co. 

383 
000 

250 
615 
200 

13  o 

5  9 

83-4 
117.7 
213.0 
262  o 

20.  6 

G.  H.  Cook,  Geol.  Rep. 

and  deep  wells  in  various  localities.  Although  there  are  so 
many  of  these  wells  in  the  United  States,  the  author  has  found 
it  extremely  difficult  to  obtain  reliable  information  with  reference 
to  the  chemical  character  of  the  water.  The  depth  of  the  well, 
whether  the  water  is  palatable  or  undrinkable,  how  it  acts  to- 
ward soap  and  in  steam  boilers — these  observations,  which  do 
not  require  the  aid  of  an  expert  or  involve  additional  expense, 
usually  complete  the  stock  of  available  information.  Table  XX 
contains  the  results  of  more  complete  analyses  obtained  by  the 
Rivers  Pollution  Commission  of  Great  Britain  from  the  examina- 
tion of  a  large  number  of  deep-well  waters  from  various  geolo- 
gical formations.  In  the  same  table  also — for  convenience  of 
arrangement — are  inserted  the  results  obtained  by  the  same 
commission  in  the  examination  of  unpolluted  waters  of  various 
descriptions  and  from  many  different  localities  in  Great  Britain. 
Table  XXI  contains  results  derived  from  the  examination  of  the 
water  from  wells  and  springs  in  the  different  geological  forma- 
tions in  Bohemia,*  the  total  number  of  analyses  being  about  125. 

*  B£lohoubek :  Ueber  den  Einflussder  geologischen  Verhaltnisse  auf  die  chemische 
Beschaffenheit  des  Quell-  und  Brunnenwassers.     Pph.  8vo,  pp.  46.    Prag,  1880. 


EXAMINATION   OF  VARIOUS   WATERS. 


TABLE  XX.— EXAMINATION  OF  DEEP- WELL  WATERS  AND  OF  UNPOLLUTED 

WATERS    FROM    VARIOUS    SOURCES. 

[Results  expressed  in  Parts  in  100,000.] 


1 

£ 

g< 

HARDNESS. 

1 

H 

H     . 

s 

w  i 

O  < 

Q 

o 

£8 

i 

<  H 

§ 

GEOLOGICAL  FOR- 

Q 

9 

H 

h 
<  £ 

3 

i 

lu 

jj 

S 

MATION. 

t/3 

u 

y 

u 

< 

a* 

D  < 

M 

| 

c 

V 

< 

K 

1 

i 

s 

|| 

JO 

£* 

0  H 

111 

1 

0) 

u 

1 

O 

o" 

H 

O 

0 

< 

* 

H 

£ 

U 

H 

(X 

H 

2 

Deep  Wells. 

DevonianRocks  and 

Millstone  Grit  

32.68 

0.068 

O.OI2 

0.005 

0.294 

0.310 

2,671 

2.70 

8.8 

8.6 

17-4 

7 

Coal  Measures  

83  .  iol 

0.119 

0.034 

0.044 

0.207 

0.278 

2,243 

18.05 

15.1 

20.6 

35-7 

9 

Magnesian   Lime- 

stone  

61.14 

0.076 

0.030 

0 

1.426 

1.456 

13,937 

4.3^ 

16.9 

26.9 

43-8 

3 

New    Red    Sand- 

stone 

30.6} 

o  036 

O.OT4 

0.003 

o  717 

°  734 

6,895 

2  -94 

7.4 

10.5 

17.9 

28 

Lias  

70.98 

0.146 

O.O27 

O.OOI 

\>    /  */ 

0.389 

0.417 

3,73° 

4.42 

21.9 

8.2 

30.1 

2 

Oolites 

33. 

0.037 

O.OIO 

O.O22 

0.625 

0.654 

6,118 

2.69 

13.8 

6.8 

20.  6 

5 

Hastings    Sand 

Green    Sand,  anc 

Weald  Clay  
Chalk 

45.20 

36.88 

0.068 
0.050 

0.014 
0.017 

O.OT6 
O.OOI 

0.196 
0.610 

0.223 
0.628 

1,864 
5,801 

5-38 
2.76 

16.8 

21.2 

10.5 

6.5 

27-3 
27.7 

20 

66 

Chalk  beneath  Lon- 

don Clay  

78.09 

0.093 

0.028 

0.048 

0.068 

0.135 

797 

15.02 

9-7 

8.7 

18.4 

13 

Thanet    Sand  and 

Drift  

53.84 

0.113 

O.O2O 

0.072 

0.116 

0.202 

i,5i7 

6.32 

14.4 

7.6 

22.0 

4 

Unpolluted  Waters. 

Class  I. 

Rain  Water  

2.95 

0.070 

O.OI5 

0.029 

0.003 

o  042 

42 

0.82 

0.4 

0.5 

0-3 

39 

Class  II. 

Upland   Surface 
Water  
Class  III. 

9.67 

0.322 

0.032 

0.002 

0.009 

0.042 

1O 

...3 

..5 

4-3 

5-4 

195 

Deep  Well  Water 
Class  IV. 

43.78 

0.061 

0.018 

0.012 

0.495 

0.522 

4,743 

5-" 

IS.8 

9.2 

25  o 

157 

Spring  Water  

28.20 

0.056 

0.013 

0   001 

0-383 

0.396 

3,595 

2.49 

II.  0 

7-5 

18.5 

198 

TABLE  XXL— BOHEMIAN  WELL  AND  SPRING  WATERS. 

[Results  expressed  in  Parts  in  100,000.] 


GEOLOGICAL 
FORMATION. 

RESULTS. 

TOTAL 
SOLIDS. 

SULPHURIC 
ACID  (SO3). 

CHLORINE. 

HARDNESS.* 

Azoic  

Max   and  Min. 

2.8-  2S.O 

O.2—      24 

o.i—  0.8 

I.q-     68 

« 

Usual  Limits 

4.6—   14  ^ 

2  ^—      4  Q 

Huronian  

Max   and  Min 

IQ.8—  tj<;  o 

I  o_      e  Q 

O  O—    2  A 

77—   1^  Q 

Usual  Limits 

•30.  5—  55  o 

<->.y—    ^.4 

Silurian 

IJ.  ^    I^O  2 

28     48  6 

47       ^7  ^ 

Usual  Limits 

66  o—  i  20  o 

22  6—  4^  4 

Carboniferous  

Max  and  Min 

•28   e    774.  O 

2  4  101  6 

O  8    2C   2 

Permian  .  . 

OT           IH 

IQ  Q      22  8 

O       *V'7 

I   ^       17  7 

Chalk  

Max  and  Min 

4  O—  IOQ  O 

o  ^     28  ^ 

n  T      fi  8 

21          7  ^ 

21   i?       7C  7 

Neogen  

Usual  Limits 

•**a     /:>•/ 

07—    68 

T    8         /I    fi 

*«3    ^y.1 

Diluvium  and  ) 
Alluvium          j-  .  .  •  • 

Usual  Limits. 

j/.»j—   q.y.  / 
I9-I-    75-5 

0.6-     5.7 

1.8-  2.3 

7.9-  24-5 

*  The  hardness  is  in  German  degrees. 


10 


CHAPTER  VIII. 

ARTIFICIAL    IMPROVEMENT   OF  NATURAL  WATER. 

NATURE  sometimes  furnishes  water  which  leaves  nothing  to 
be  desired  in  respect  to  quality,  but,  unfortunately,  the  best 
water — such  as  is  sometimes  derived  from  springs  and  not  un- 
frequently  from  the  ground  water — is  apt  to  be  limited  in 
amount,  and,  very  generally,  a  supply  sufficient  in  quantity  can 
be  procured  only  from  a  source  possessing  some  undesirable 
qualities.  Although  a  water  which  is  polluted  to  any  consid- 
erable extent  by  sewage  is  not  capable  of  purification  by  any 
process  practicable  on  the  large  scale,  so  that  it  can  safely  be 
used  for  domestic  supply,  the  character  of  many  natural  waters 
may  be  sensibly  improved  by  proper  treatment.  Again,  there 
are  circumstances  under  which  it  becomes  absolutely  necessary 
to  use  a  bad  water  or  none  at  all,  and  in  such  cases  purification 
must  be  accomplished  if  possible. 

We  shall  consider  various  methods  of  improving  potable 
water  under  the  following  heads  : 

1.  Sedimentation  and  storage. 

2.  Filtration  (on  the  large  and  on  the  household  scale). 

3.  Clark's  process  for  softening  hard  water. 

4.  Other  (chemical)  processes. 

5.  Distillation. 

Sedimentation  and  Storage. 

When  a  stream  or  other  body  of  surface  water  is  used  as  a 
source  of  supply,  the  best  way — speaking  solely  from  a  sanitary 
point  of  view — is  to  pump  directly  from  the  source  into  the  dis- 
tribution without  the  intervention  of  settling  basins  and  reser- 
voirs. This  is  not,  however,  generally  practicable.  In  some 
cases  the  general  or  occasional  turbid  character  of  a  stream 
renders  sedimentation  necessary,  and  in  other  cases  storage 
basins  are  necessary  in  order  that  the  stream  may  furnish  a  suf- 
ficient quantity  of  water  during  the  dry  season. 


SEDIMENTATION.  147 

Sedimentation. — The  particles  of  suspended  matter  which 
render  a  stream  turbid  or  muddy,  regularly  or  in  times  of  flood, 
are  of  a  greater  specific  gravity  than  the  water  itself,  and  settle 
out  more  or  less  completely  if  the  water  be  allowed  to  stand 
quiet  for  a  time.  Lakes  and  ponds  are  natural  settling  basins, 
and  have  this  advantage  over  running  streams,  that  they  are 
much  less  liable  to  be  rendered  turbid  by  freshets  ;  they  are  not, 
however,  usually  entirely  free  from  floating  particles,  but  the 
suspended  matter  in  this  case  cannot  be  removed  except  by 
filtration. 

Some  figures  have  been  already  given  in  Table  VII  to  show 
the  various  amounts  of  suspended  matter  in  certain  rivers.  It 
is  well  known  that  the  water  of  many  of  the  rivers  in  this  coun- 
try, especially  in  the  West,  is  not,  in  its  natural  condition, 
acceptable,  if  indeed  it  can  be  regarded  as  at  all  suitable  for 
use.  It  is  said*  that  the  sediment  in  the  Mississippi  (or  rather 
the  Missouri)  at  St.  Louis  amounts  at  times  to  1.8  per  cent  of 
the  bulk  of  the  water.  About  94.5  per  cent  of  the  sediment  is 
deposited  within  24  hours  in  still  water  at  ordinary  stages  of  the 
river,  but  for  two  months  in  the  year,  during  floods,  there  is  so 
much  fine  sediment  that  no  amount  of  settling  will  clarify  the 
water. 

It  is  desirable  to  remove  the  suspended  matter,  not  simply 
on  aesthetic  grounds,  because  it  renders  the  water  less  acceptable 
to  the  eye,  but  also  because  particles  of  gritty  mineral  matter,  or 
even  of  clay,  often  cause  diarrhoea,  especially  in  the  case  of  per- 
sons not  in  the  habit  of  using  the  water,  to  which  many  persons 
do  become  accustomed  by  use.  Where  thorough  filtration  is  for 
any  reason  impracticable,  sedimentation  serves  a  useful  purpose. 

There  are  now  at  St.  Louis  four  settling  basins,  600  x  278  feet, 
and  19  feet  deep.  The  floors  are  paved  with  brick  on  edge  and 
slope  toward  the  center  and  the  river  side.  The  basins  are  used 
alternately,  one  being  drawn  from,  one  filling  and  two  settling, 
or  one  settling  and  one  being  cleaned.  The  sediment  is  removed 
from  each  basin  about  once  in  four  months,  some  16  inches 
being  collected  in  that  time.  The  sediment  is  floated  off  with  a 
stream  of  water,  at  a  cost  of  from  0.84  cent  (1879)  to  I«°5 
per  cubic  yard. 


Engineering  News,  1881,  p.  142. 


148 


WATER   SUPPLY. 


As  an  accompaniment  of  a  scheme  of  filtration,  settling  basins 
are  in  many  cases  essential.  Where  a  stream  is  subject  to 
sudden  and  transient  periods  of  turbidity,  besides  serving  in  their 
proper  capacity,  they  may  also  serve  as  storage  basins  and  make 
it  possible  to  avoid  altogether  taking  water  from  the  stream 
when  it  is  at  its  worst. 

In  following  the  variations  of  a  turbid  water,  or  in  tracing  the 
progress  of  sedimentation,  estimation  of  the  amount  of  turbidity 
is  usually  made  by  simply  looking  through  a  certain  depth  of  the 
water  in  a  tube  or  other  glass  vessel.  Several  attempts  have 
been  made  to  reach  more  accurate  results,  and  Grahn  and  Sal- 
bach*  have  proposed  to  apply  the  principles  of  photometry  to 
the  solution  of  the  problem. 


FIG.  27. — SALBACH'S  PHOTOMETER,  ELEVATION.     (FROM  FISCHER.) 


FIG.  28.— SALBACH'S  PHOTOMETER,  PLAN.    (FROM  FISCHER.) 

Figures  27  and  28  represent  Salbach's  arrangement  of  the 
photometer.  P  carries  a  disk  of  paper  on  which  a  spot  has  been 
made  transparent  by  means  of  oil  or  stearine ;  at  the  beginning 
P  is  set  at  the  zero  point  of  the  scale,  and  the  burners,  B  B,  reg- 
ulated so  as  to  give  an  equal  amount  of  light.  C  is  a  leaden  box 
the  glass  sides  of  which  are  exactly  parallel,  and  100  millimeters 
apart.  When  C  is  filled  with  turbid  water  a  portion  of  the  light 

*  Journal  fur  Gasbeleuchtung  und  Wasserversorgung,  xx  (1877),  p.  545. 


STORAGE. 


149 


given  by  the  right-hand  burner  is  cut  off,  and  the  screen  P  must 
be  moved  nearer  to  this  weakened  source  of  light  in  order 
that  the  illumination  on  both  sides  may  be  equal.  From  the 
distance  through  which  the  screen  must  be  moved,  it  is  possible 
to  calculate  the  loss  of  light,  and  thus  to  obtain  an  expression 
for  the  amount  of  turbidity  of  the  water. 

Storage. — Some  of  the  disadvantages  to  which  stored  water  is 
subject  in  ponds  and  impounding  reservoirs  have  already  been 
indicated — such,  for  instance,  as  undesirable  increase  of  temper- 
ature, growth  of  noxious  algae,  etc.  On  the  other  hand,  there 
are  certain  advantages  in  storing  surface  waters  in  clean  deep 
basins  exposed  to  the  sun  and  air.  When  strongly  colored  sur- 
face waters  are  thus  stored,  the  dissolved  organic  matter  under- 
goes chemical  change,  and  a  portion  of  it,  being  removed  from 
solution,  settles  out  as  a  sediment ;  at  the  same  time  the  color 
becomes  less  marked. 

In  order  to  compare  and  estimate  the  depth  of  color  of  vari- 
ous waters,  or  of  the  same  water  at  various  times,  an  instru- 
ment was  invented  and  used  by  a  medical  commission  which 
investigated  a  number  of  sources  of  water  supply  proposed  for 
the  city  of  Boston.*  "The  instrument  consists  of  two  tubes,  B 
and  D  (Fig.  29),  sliding  water-tight  one  within  the  other,  the 
lower  end  of  each  tube  being 
closed  with  a  disk  of  plate 
glass.  Into  the  large  tube,  B, 
just  above  the  plate  glass  disk, 
is  inserted  a  small  piece  of 
tubing  which  terminates  in  a 
funnel  -  shaped  receiver,  A. 
Water  poured  into  this  re- 
ceiver will  therefore  pass  into 
the  space  between  the  two 
glass  disks,  entirely  filling  the 
outer  tube  when  the  inner 
tube  is  withdrawn,,  and  again 


FIG.  29. 


returning  to  the  receiver  when  the  inner  tube  is  pushed  down  so 
that  the  glass  disks  come  in  contact  with  each  other.     Through 

*  Report  of  the  Medical  Commission  upon  the  Sanitary  Qualities  of  the  Sudbury, 
Mystic,  Shawshine  and  Charles  River  Waters.     City  Document,  No.  102.     Boston, 

1874, 


I$0  WATER  SUPPLY. 

an  opening  near  the  upper  end  of  the  smaller  tube,  D,  is  inserted 
one  end  of  a  rhombic  prism,  £,  in  which  total  internal  reflection 
takes  place  twice. 

"  This  prism  extends  half  way  across  the  inner  tube,  D,  so 
that  an  eye,  looking  through  the  eye-piece,  G,  sees  the  field  of 
vision  nearly  half  filled  by  the  surface  of  the  prism.  This  ap- 
pearance is  represented  at  /.  The  eye-piece,  G,  contains  a  single 
lens,  which  is  focused  upon  the  upper  surface  of  the  prism.  The 
position  and  angles  of  the  prism  are  such  that  a  ray  of  light  out- 
side of,  and  parallel  to,  the  tube  B,  is  reflected,  first  directly  into 
the  tube  D,  and  then  parallel  to  its  axis,  thus  emerging  from  the 
prism  and  entering  the  eye-piece  alongside  of  the  rays  of  light 
which  have  passed  through  the  two  plate  glass  disks.  It  will 
thus  be  seen  that  the  conditions  for  comparing  the  color  and 
intensity  of  these  two  sources  of  light  are  as  favorable  as  pos- 
sible. A  piece  of  white  card,  C,  fastened  at  the  lower  end  of  the 
larger  tube,  throws  a  uniform  white  light  through  the  tubes 
B  and  D,  and  also  along  the  outside  of  the  tube  B,  into  the 
prism  E. 

11  In  using  this  instrument,  a  piece  of  brownish-yellow  glass,  F, 
is  placed  in  front  of  the  prism  E,  and  the  water,  whose  color  is 
to  be  determined,  is  poured  into  the  receiver  A.  The  inner  tube 
is  then  withdrawn  until  the  column  of  water  between  the  two 
glass  disks  is  sufficiently  long  to  give  to  the  light  passing  through 
it  a  color  equal  to  that  imparted  by  the  colored  glass  F  to  the 
light  passing  through  the  prism  E.  The  length  of  this  column 
of  water,  which  will,  of  course,  vary  inversely  with  the  depth  of 
color,  can  be  determined  by  means  of  the  scale  on  the  inner 
tube  D.  By  this  means,  the  relative  intensity  of  color  of  various 
specimens  of  water  may  be  determined  with  considerable  ac- 
curacy." 

Aeration. — Although  a  water  colored  by  vegetable  matter 
loses  color  when  exposed  to  sunlight  in  closed  vessels,  it  is  prob- 
able that  the  changes  which  take  place  in  storage  basins  are  due 
partly  to  the  action  of  the  air.  There  is  no  doubt  that  the  pas- 
sage of.  the  water  over  natural  falls  or  artificial  dams  tends  to  its 
improvement,  or  that  the  stagnation  of  water  in  "  dead  ends,"  or 
in  small  reservoirs  without  circulation,  tends  to  its  deterioration. 
In  the  larger  reservoirs  and  ponds  the  winds  play  an  important 
part  in  agitating  and  aerating  the  water,  but  it  is  very  doubtful 


FILTRATION.  !$! 

if  any  scheme  for  artificially  aerating  the  water  would  accom- 
plish enough  to  pay  for  the  outlay  involved. 

Filtration. 

The  filtration  of  water  on  the  large  scale  has  been  practised 
in  England  and  on  the  continent  of  Europe  for  many  years,  and 
has  become  very  general  in  cases  where  the  supply  is  taken  from 
streams  or  ponds.  From  statistics  which  were  laid  before  the 
Diisseldorf  meeting  of  the  German  Public  Health  Association 
(in  1876)  by  Engineer  Grahn,*  it  would  seem  that  in  Germany, 
since  1858,  there  has  been  no  town  of  considerable  size  supplied 
with  unfiltered  river  water,  while  the  increase  with  reference  to 
other  sources  of  supply  may  be  seen  from  the  following  data : 

TOTAL  NUMBER   OF  INHABITANTS   IN   80  TOWNS   OF   GERMANY,    GERMAN-AUSTRIA, 

AND    SWITZERLAND 


SUPPLIED  WITH 

1858. 

1876. 

Unfiltered  river  water                              . 

460  ooo 

460  ooo 

Filtered  river  water  

i  060  oco 

i  607  ooo 

Spring  and  ground  water  (by  gravitation)  

25  ooo 

i  510  ooo 

AC  OOO 

I  7IO  OOO 

In  the  United  States  very  little  has  yet  been  done  in  the  way 
of  systematic  filtration  on  the  large  scale,  although,  in  some  lo- 
calities, attempts  have  been  made  to  improve  the  condition  of 
the  water  by  intercepting  some  of  the  suspended  matter. 

Filter  beds,  as  usually  constructed,  are  water-tight  basins 
some  ten  feet  or  more  in  depth,  the  sides  built  of  masonry,  and 
the  bottom  puddled  or  made  of  concrete,  or  paved  with  brick 
and  cemented.  The  area  may  be  from  20,000  to  50,000,  or  in 
some  cases  even  150,000  square  feet.  In  building  up  the  filter- 
ing bed,  provision  is  first  made  for  the  ready  collection  of  the 
water  by  constructing  upon  the  floor  of  the  basin  drains  or 
channel-ways  of  stone  or  brick  laid  dry;  then  follows  a  layer  of 
broken  stone,  the  fragments  being  three  or  four  inches  in  diame- 
ter. This  is  succeeded  by  gravel  screened  so  as  to  be  of  uniform 
size,  a  layer  of  coarse  being  followed  by  one  or  more  layers  of 
finer  material ;  upon  the  gravel  rests  sand,  likewise  separated 

*  See  the  Deutsche  Vierteljahrsschr.  fur  affentl.  Gesundheitspflege,  ix  (1877),  p. 
108. 


I52  WATER   SUPPLY. 

into  layers  of  uniform  size.  The  exact  thickness  of  the  different 
layers,  and  the  extent  to  which  the  separation  into  the  different 
sizes  is  carried,  are  subject,  of  course,  to  considerable  variation. 

The  water  stands  several  feet  deep  over  the  surface  of  the 
sand,  and  is  allowed  to  flow  down  through  the  filter  at  such  rate 
as  experience  shows  to  be  most  advantageous.  Naturally,  when 
the  sand  is  clean,  a  greater  quantity  of  water  can  be  passed  in  a 
given  time  than  when  the  sand  has  become  clogged ;  practice 
differs  as  to  the  maximum  rate,  but  it  is  seldom  over  six  inches, 
vertically,  per  hour,  and  often  less.  At  the  rate  mentioned,  each 
square  foot  of  surface  would  deliver  12  cubic  feet  (or  89^  United 
States  gallons)  per  day. 

When  the  beds  become  clogged  so  as  no  longer  to  filter  with 
sufficient  rapidity,  the  water  is  drawn  out  from  the  beds,  and  the 
upper  layer  of  sand,  for  a  depth  of  one-half  or  three-quarters  of 
an  inch,  is  removed.  When  by  successive  parings  the  thickness 
of  the  sand  has  been  considerably  reduced,  that  which  has  been 
removed  is  washed  and  replaced  so  as  to  restore  the  original 
thickness,  the  waste  of  washing  being  made  up  with  fresh  sand. 

Principles   of  Sand  Filtration. 

Having  thus  stated  briefly  the  main  features  of  ordinary 
sand  filtration,  we  will  proceed  to  discuss  the  principles  which 
govern  filtration  in  general,  and  afterward  consider  certain 
special  points  with  reference  to  the  successful  carrying  out  of 
the  process.  For  this  purpose  we  shall  consider  the  "  impuri- 
ties "  of  ordinary  water  as  divided  into  three  classes  :  first,  the 
suspended  matters,  whether  of  mineral,  animal  or  vegetable 
origin ;  second,  the  dissolved  mineral  or  saline  matters ;  third, 
the  dissolved  organic  matters. 

The  action  which  takes  place  when  an  ordinary  water  is 
passed  through  a  sand  filter  is  threefold.  In  the  first  place,  the 
most  obvious  action  is  the  arresting  of  suspended  particles  of 
solid  matter  which  are  too  large  to  pass  through  the  pores  of 
the  filter.  The  second  action  partakes  something  of  the  charac- 
ter of  sedimentation,  and  may  be  well  illustrated  by  the  follow- 
ing experiment: 

Take  two  jars  of  equal  size,  and  fill  one  of  them  with  frag- 
ments of  broken  rock  as  large  as  half  a  fist,  or  with  very  coarse 
gravel,  arranging  the  material  so  that  a  syphon  can  be  inserted 


PRINCIPLES   OF  FILTRATION. 


153 


FIG.  30. 


as  shown  in  the  figure.     Prepare  now  a  quantity  of  a  turbid  liquid 
by    stirring     up 

L 


some  fine  clay  in 
water  and  allow- 
ing the  coarser 
particles  to  sub- 
side. With  this 
turbid  water  fill 
both  jars  and  al- 
low them  to 
stand  for  twelve 
or  fifteen  hours. 
Then,  by  means 
of  syphons  reach- 
ing to  the  same 
depth  in  the 
jars,  carefully  remove  a  quantity  of  water  from  each.  It  will  be 
found  that  the  water  from  the  jar  containing  the  broken  stone  is 
perceptibly  clearer  than  the  other. 

The  same  thing  may  be  shown  by  allowing  a  turbid  water  to 
flow  very  slowly  through  a  trough  filled  with  broken  stone.  In 
these  cases  the  interstices  between  the  fragments  are  so  many  set- 
tling chambers,,  as  it  were,  and  the  particles  of  the  clay  deposit 
not  only  upon  the  floor  of  these  chambers,  but  also  on  the  sides 
and  roof,  being  drawn  thereto  by  a  sort  of  attraction.  In  the 
case  of  a  sand  filter,  the  interstices  are  small  and  very  numerous. 

The  third  sort  of  action  which  takes  place  in  the  porous 
material  of  a  filter  is  the  removal  of  substances  which  are  actually 
dissolved  in  the  water.  As  far  as  the  mineral  or  saline  matters 
are  concerned,  this  action  is  trifling,  although  not  inappreciable 
with  certain  filtering  media:  with  sand  filters  we  can  say  that 
there  is,  practically,  no  effect  on  the  dissolved  mineral  matter, 
unless  there  is  opportunity  for  a  chemical  change  to  take  place. 
Thus,  it  seems  to  be  well  attested,  that  a  hard  water  containing 
bicarbonate  of  lime  may  deposit  carbonate  of  lime  in  the  filter, 
owing  to  the  escape  of  carbonic  acid.*  Sometimes  the  amount 

*  See,  for  example,  Lefort,  Chimie  Hydrologique,  pp.  165,  200.  It  has  also 
been  sho-.vn  by  Schloesing  (see  Assainissement  de  la  Seine,  2ieme  partie,  Enquete,  p. 
191),  that  at  some  depth  in  soil  which  had  been  irrigated  with  sewage,  there  were 
formed  crystals  of  carbonate  of  lime,  owing  to  the  escape  of  carbonic  acid  from  the 
sewage  water,  which  contained  a  small  proportion  of  bicarbonate  of  lime  in  solution. 


154  WATER   SUPPLY. 

of  mineral  matter  may  be  greater  in  the  filtered  than  in  the  un- 
filtered  water,  if  the  material  of  the  bed,  the  graveland  stones, 
contain,  as  they  often  do,  soluble  ingredients. 

With  reference  to  the  dissolved  organic  substances,  it  may 
be  said  that  a  small  but  appreciable  amount  may  be  removed  by 
a  well-conducted  sand  filtration ;  the  action  may  be  explained  in 
two  ways.  In  the  first  place,  most  porous  substances  possess 
the  power  of  removing  certain  kinds  of  organic  matter  by  some- 
thing which  may  be  called  adhesion.  The  absorptive  power  for 
any  substance  is  limited  and  soon  reached,  and  the  substance 
thus  removed  may  by  appropriate  means  be  again  brought  into 
solution.  Quartz  sand,  as  we  should  infer,  possesses  the  power 
to  a  slight  degree  only.  In  the  second  place,  dissolved  organic 
matter  is  removed  in  the  sand  filter  by  oxidation.  The  sub- 
stance is  actually  burned  more  or  less  completely,  in  part  by  the 
oxygen  held  in  solution  in  the  water,  and  in  part  by  the  air  en- 
tangled in  the  interstices  of  the  sand.  Although  in  filling  the 
beds  with  water,  great  care  is  taken  to  displace  the  air  gradually, 
and  as  completely  as  possible,  there  must  always  some  remain  in 
the  concavities  of  the  individual  grains  of  sand  and  otherwise 
entangled.  The  extent  of  the  action  of  a  sand  filter  in  this 
direction  depends  not  only  on  the  fineness  of  the  filtering 
medium,  and  the  rate  at  which  the  filtration  takes  place,  but  also 
and  in  considerable  measure  upon  the  frequency  with  which  the 
filter  is  cleansed.  The  cleansing  of  the  filter  not  only  removes 
the  accumulation  of  organic  matter,  which,  if  allowed  to  remain, 
would  tend  to  injure  the  water,  but  also  involves  the  aeration  of 
the  sand,  at  least  to  a  considerable  depth. 


Details  of  Practice. 

We  now  proceed  to  some  more  particular  details  of  the  prac- 
tice of  sand  filtration.  The  quality  of  the  sand  employed  is  by 
no  means  a  matter  of  indifference,  and  in  the  case  of  waters 
which  usually  or  occasionally  carry  finely  divided  clay  in  suspen- 
sion, a  great  deal  depends  upon  having  proper  sand  and  a  slow 
rate  of  filtration.  It  may  be  said,  in  general,  that  the  sand  em- 
ployed should  be  made  up  mainly  of  grains  from  ^  of  a  milli- 
meter to  i  millimeter  in  diameter,  and  the  more  uniform  the  size 


DETAILS   OF   PRACTICE.  155 

of  the  grains  the  better.*  A  considerable  proportion  of  larger 
grains  does  no  harm,  but  the  smaller  particles  should  be  washed 
out  before  the  sand  is  used  ;  as  a  rule,  sand  that  has  been  used 
and  washed  is  better  than  fresh  sand.  As  the  fineness  of  the 
sand  increases,  its  efficiency  as  a  filter  increases,  but  the  difficulty 
and  cost  of  filtration  increase  likewise,  and  more  frequent  cleans- 
ing is  necessary.  To  obtain  the  best  and  most  economical  results 
with  a  given  water,  special  experiments  should  be  made  with 
reference  to  the  sand  best  fitted  for  that  water — although,  to  be 
sure,  it  is  not  always  possible  to  command  that  which  would  be 
absolutely  the  best. 

While  it  is,  in  general,  true  that  the  upper  layer  of  sand  does 
most  of  the  work  in  intercepting  the  various  floating  matters  in 
the  water,  it  does  not  do  the  whole  under  the  conditions  which 
occur  in  ordinary  practice.  Examination  shows  that  the  sand  is 
somewhat  affected  to  a  greater  depth,  and  it  may  occasionally  be 
necessary  to  renew  all  the  sand.  The  very  fact,  which  will 
appear  presently,  that  in  all  actual  works  there  are  times  when 
the  water  is  imperfectly  clarified,  shows  that  the  interior  of  a 
sand  filter  must  in  time  become  more  or  less  foul. 

It  may  perhaps  be  asked,  why,  if  the  work  is  practically  done 
by  the  first  few  inches  of  sand,  it  is  necessary  to  bestow  such 
care  on  the  construction  of  the  beds,  and  on  the  arrangement  of 
the  materials  employed. 

In  the  first  place,  it  is  a  well-recognized  fact,  that  the  worst 
possible  filter  is  one  in  which  the  portions  of  material  of  different 
sizes  are  indiscriminately  mixed.  "  The  different  degrees  of  fine- 
ness in  the  materials  beneath  the  sand,  and  their  several  thick- 
nesses, were  intended  first  to  prevent  the  fine  sand  from  following 
the  water  downward  into  the  drains,  and  next  to  insure  the 
presence  of  such  a  body  of  clean  water  below  the  surface  of  the 
filter  as  would  penetrate  the  numerous  joints  and  openings  of  the 
drains,  and  keep  them  full,  without  creating  anywhere  currents 
or  veins  of  water  of  any  perceptible  difference  of  velocity. 

"  With  the  drains  much  nearer  to  the  body  of  the  sand,  it 
will  be  understood  that  the  tendency  of  the  water  would  be  to 
flow  through  the  filtering  material  more  rapidly  just  over  the 

*  Mr.  Charles  Greaves,  of  the  East  London  Works,  says  ' '  sand  that  would  go 
through  a  screen  consisting  of  32  or  33  No.  10  wires  in  6  inches,"  is  the  best,  accord- 
ing to  English  experience. 


I56 


WATER   SUPPLY. 


pipe  than  at  five  feet  on  either  side  of  it.  The  distance  through 
which  it  had  to  travel  might  be  so  short  as  to  induce  its  concen- 
tration. The  low  velocity  at  which  the  water  flows  through  the 
filter,  the  uniformity  of  fineness  in  the  sand,  and  the  distance  of 
the  collecting  drains  from  its  surface,  all  work  together  to  pro- 
duce that  regularity  of  action  over  the  entire  filter  bed  upon 
which  its  perfection  depends."  * 

The  rate  of  filtration  must  be  determined  by  the  character  of 
the  water  and  the  condition  of  the  filters.  The  maximum  rate 
given  on  page  152  as  89^  U.  S.  gallons  per  square  foot  in  24 
hours  would  be  equivalent  to  about  3^  cubic  meters  per  square 
meter  of  surface.  The  practice  of  most  works  falls  considerably 
below  this  as  an  average  rate  ;  thus  at  Altona,  where,  to  be  sure, 
the  constantly  turbid  water  of  the  Elbe  is  filtered,  the  average 
rate  is  only  1.5  cubic  meters  per  square  meter  of  surface  in  24 
hours.  It  is  stated  that  the  sand  here  employed  is  coarser  than 
necessary,  and  that  with  somewhat  finer  sand  a  more  rapid  rate 
of  filtration  would  be  possible,  f 

There  is  considerable  difference  in  practice  as  to  the  depth  of 
water  kept  upon  the  surface  of  the  beds  and  the  head  under 
which  filtration  takes  place.     Moreover,  the  head  under  which 
the  water  is  filtered  varies  at  any  works  according  to  the  condi- 
tion of  the  sand.     The  clear-water 
well  is  generally  so  arranged    that 
the  height    of  water  in  it  can  be 
lowered  at  pleasure  ;  and  the  head 
under   which  the  water  is  filtered 
is  the  difference  between  the  level 
in  the  bed  and  in  the  clear-water 
well,  as  may  be  seen,  in  the  accom- 
panying  cut,   where    the   head    is 
measured  by  the  distance  between 
a  and  b.     While  the  beds  are  clean, 
a  difference  of  from  9  to  12  inches 
suffices  to  cause  a  proper  rate  of 
FIG.  31.  flow  ;   as   they  become   clogged   a 

much  greater  pressure  is  required,  but  it  is  not  desirable  to  in- 


*  Kirkwood,  Filtration  of  River  Waters,  p.  10. 
f  Samuelson,  Nachschrift  to  German  edition  of  Kirkwood's  Report. 
1876. 


Hamburg, 


DETAILS   OF  PRACTICE.  157 

crease  the  pressure  to  too  great  an  extent,  as  the  sand  is  thereby 
fouled  to  a  greater  depth  and  compacted  more  than  is  desirable. 

The  frequency  with  which  it  is  necessary  to  cleanse  the  beds 
depends  upon  circumstances.  In  the  worst  stages  of  the  English 
rivers  a  filter  bed  has  to  be  cleaned  once  a  week,  rarely  oftener. 
When  the  rivers  are  free  from  turbidity,  cleansing  may  not  be 
necessary  more  than  once  a  month,  or»in  some  cases  once  in  two 
months.  The  general  method  of  cleaning  has  already  been  indi- 
cated. In  some  places  the  practice  is  different.  At  Zurich,  in 
Switzerland,  it  is  the  custom  to  clean  the  beds  by  forcing  the 
water  in  a  reverse  direction  through  the  filters.  Workmen,  clad 
in  rubber  clothing,  then  stir  up  the  upper  surface  of  the  sand 
with  forks,  and  the  collected  slime  is  washed  off  and  floated 
away.  This  requires  an  abundance  of  water,  and  the  ability  to 
command  the  requisite  pressure.  One  would  suppose  also  that 
it  would  involve  some  danger  of  disturbing  the  arrangement  of 
the  filtering  material. 

Certain  recently  published  details  of  the  manner  in  which  the 
filtration  works  at  Berlin*  are  conducted,  are  of  considerable  in- 
terest, as  the  condition  of  things  is  similar  to  that  which  exists  in 
some  of  the  surface  waters  of  our  Eastern  States.  The  water  of 
the  Spree,  besides  being  somewhat  polluted  by  sewage  and  being 
in  a  constant  roily  condition,  possesses,  especially  in  time  of 
flood,  a  deep  brownish-yellow  color,  and,  at  times,  a  peculiar 
pondy  taste  due  to  vegetable  extractive  matter.  Moreover,  from 
spring  until  fall,  a  more  or  less  copious  growth  of  algce  adds  to 
the  disagreeable  character  of  the  water,  similar  to  those  described 
and  figured  on  page  86. 

The  filter  beds  are  construced  on  the  English  model  and  are 
eleven  in  number — three  covered  and  eight  uncovered — having  a 
total  area  of  37,000  square  meters.  The  filtration  is  carried  on 
at  a  very  slow  rate.  The  water  is  used,  of  course,  in  varying 
quantities  from  hour  to  hour,  and,  on  account  of  the  small  size 
of  the  clear-water  reservoir,  a  constant  rate  of  filtration  is  impos- 
sible ;  the  maximum  rate  is,  however,  not  over  o.i  meter  down- 
ward per  hour.  For  the  greater  part  of  the  time  i  square  meter 

*  Mittheilungen  uber  nattlrliche  und  kilnstliche  Sandfiltration.  Nach  Betriebs- 
resultaten  der  Berliner  Wasservverke  vor  dera  Stralauer  Thor,  bearbeitet  von  C.  Piefke, 
Betriebs-Ingenieur.  8vo,  pp.  75.  Berlin,  1881.  A  review  and  abstract  of  this 
pamphlet  appeared  in  the  Journal  of  the  Franklin  Institute,  December,  1881. 


158  WATER   SUPPLY. 

of  sand  surface  is  not  required  to  furnish  much  more  than  one 
cubic  meter  of  water  in  twenty-four  hours.  This  would  be  at 
the  rate  of  only  24!  U.  S.  gallons  per  square  foot,  and  very  much 
less  than  is  the  practice  in  many  other  places.  The  head  under 
which  filtration  takes  place  is  seldom  more  than  0.5  meter  (say 
20  inches),  but  even  with  this  low  pressure  and  slow  delivery  it 
has  been  found  impossible,  with  clean  sand  alone,  to  filter  the 
water  satisfactorily.  If  the  unfiltered  water  be  allowed  to  stand 
a  fortnight  or  so,  although  the  larger  of  the  suspended  particles 
will  have  settled  to  the  bottom,  the  water  still  retains  a  milky 
appearance,  and  sand  alone  cannot  remove  the  exceedingly  fine 
particles  to  which  this  appearance  is  due.  On  this  account  the 
water  from  a  freshly  cleaned  filter  is  not  used  at  once,  but  is  al- 
lowed to  stand  on  the  bed  and  then  to  pass  through  very  slowly 
until  a  thin  coating  has  formed  on  the  surface  of  the  sand.  This 
coating  is  essential  to  the  removal  of  the  finest  particles  from  the 
water  subsequently  filtered.  Of  course,  as  the  coating  becomes 
thicker  the  filtration  becomes  more  difficult  until  it  partially 
stops  and  the  filter  is  "  dead." 

As  has  been  hinted  above,  the  great  trouble  in  summer  is 
from  the  abundance  of  small  algae  which  soon  clog  the  filter. 
When  the  algae  are  absent,  a  square  meter  of  surface  usually  fil- 
ters 20  cubic  meters  before  cleaning  is  necessary  ;  but  in  summer 
the  capacity  is  not  over  10  cubic  meters  to  the  same  area,  and 
when  a  slimy  coating  of  decayed  algae  covers  the  surface  of  the 
sand  it  becomes  impossible,  under  the  pressure  commonly  em- 
ployed, to  pass  more  than  2  cubic  meters  of  water  through  I  square 
meter  of  sand  surface.  In  the  Berlin  beds  the  thickness  of  the 
sand  is  600  millimeters  (about  2  feet).  At  each  cleaning  the  sand 
is  removed  for  a  depth  of  about  10  millimeters,  but  fresh  sand 
is  not  returned  to  the  bed  until  only  about  200  millimeters  of  the 
original  thickness  remain.  The  foul  sand  is  allowed  to  stand  ex- 
posed to  the  air  until,  by  decay,  the  organic  matter  has  lost  its 
slimy  character ;  it  is  then  washed  and  eventually  replaced  upon 
the  beds.  When  the  filters  are  emptied  the  water  is  drawn  com- 
pletely off,  and  by  successive  and  systematic  stirring  nearly  the 
entire  thickness  of  the  sand  is  exposed  to  the  air,  in  order  that 
the  small  amount  of  organic  matter  which  was  not  retained  at 
the  surface  may  be  oxidized  and  destroyed.  With  the  same 
object  in  view,  the  air  is  allowed  to  circulate  freely,  for  several 


PRACTICAL  RESULTS   OF  FILTRATION. 


159 


days  if  possible,  through  the  coarser  underlying  material.  These 
filters  are  filled  from  below  with  filtered  water,  and  then  the 
water  is  passed  through  slowly  and  is  allowed  to  waste  for  sev- 
eral days. 

Practical  Results  of  Artificial  Filtration. 
As  far  as  the  suspended  matter  is  concerned,  the  chief  diffi- 
culty in  obtaining  a  bright  and  clear  filtered  water  lies  with  the 
finely  divided  clay  which  forms  the  turbidity  of  many  streams, 
especially  at  times  of  high  water.  The  Berlin  experience  has 
already  been  alluded  to.  The  following  table,  taken  from  the 
Sixth  Report  of  the  Rivers  Pollution  Commission  (p.  215),  will 
give  an  idea  of  the  efficiency  of  the  filtration  as  practised  by  the 
various  London  companies.  The  observations  being  made  on 
monthly  samples,  the  statements  of  the  table  will  perhaps  hardly 
give  a  just  idea  of  the  results  obtained  day  by  day ;  but  they 
will  serve  to  indicate  the  fact  that  the  mere  possession  of  filter- 
beds  does  not  secure  perfectly  clear  water  at  all  times. 

TABLE  XXII. — THAMES  AND  LEA  WATER — COMPARATIVE  EFFICIENCY  OF  DIF- 
FERENT RATES  OF  FILTRATION  DURING  THE  YEARS  1868  to  1873,  INCLUSIVE. 


NAME  OF  COMPANY. 

Maximum  rate 
of  Filtration 
expressed  in 
inches  per 
hour. 

NUMBER  OF  MONTHLY  OCCASIONS  WHEN— 

Clear. 

Slightly 
Turbid. 

Turbid. 

Very 
Turbid. 

THAMES. 
Chelsea.     .        .  .          . 

7.27 
4.71 
6.00 
6.97 

12.00 

5-00 

3-85 

49 

75 
4i 
55 
42 

70 
51 

15        . 
O 

24 
14 
II 

4 

18 

5 

0 

5 
7 

12 
0 

3 

6 
O 

4 
o 

10 

o 

2 

West  Middlesex  

Southwark  and  Vauxhall  
Grand  Junction.                  .  . 

Lambeth.  

LEA. 
New  River 

East  London   

As  already  explained,  in  addition  to  clarification  of  the  wa- 
ter, ordinary  filtration  does  remove  an  appreciable  amount  of 
organic  matter  previously  held  in  solution.  In  addition  to  the 
explanation  given  on  page  153,  it  may  be  said  that  a  part  of  the 
effect  which  has  been  observed  may  be  ascribed  to  the  oxide  of 
iron,"*  and  perhaps  other  minerals,  which  exist  in  the  sand  used 
for  filtration,  the  sand  being  seldom  or  never  pure  quartz. 

The  effect  of  filtration  on  the  water  of  the  Thames  and  Lea 


*  This  is  the  view  of  Thomas  Spencer,  the  inventor  of  the  so-called  "  carbide  of 
iron,"  used  sometimes  as  a  filtering  medium.     See  page  166. 


i6o 


WATER  SUPPLY. 


has  been  made  the  subject  of  experiment  by  the  Rivers  Pollu- 
tion Commission  and  others.  The  following  table  includes  some 
of  the  results  obtained : 


TABLE  XXIIL— OBSERVATIONS  ON  THE  WATER  OF  THE  VARIOUS  LONDON 

COMPANIES. 

[Results  expressed  in  Parts  per  100,000.] 


COMPANY. 

DATE. 

UN  FILTERED 
OR 

FILTERED. 

TOTAL  SOLID 
RESIDUE  AT 

I20°-I300  C. 

ORGANIC 

CARBON. 

ORGANIC 

NITROGEN. 

< 

| 

<! 

NEW  RIVER. 

1873. 

New  River,  Stoke  Newington  

**/jr 

Jan.  25.  . 

jUnf.. 
i  Filt'd. 

31.98 
30.16 

0-350 
0.246 

0.084 
0.042 

0.004 
O 

New  River,  New  River  Head  

Jan.  27.  . 

JUnf.. 
{  Filt'd. 

31.96 
3I-56 

0.330 
0.242 

0.061 
0.043 

0.004 

o 

THAMES  RIVER. 

Southwark,  Hampton  

Jan.  31.. 

JUnf.. 
i  Filt'd. 

32.OO 
31.56 

0.321 
0.273 

0.063 
0.042 

0.001 
0 

Chelsea  

Jan.  31.. 

JUnf.. 
\  Filt'd. 

3T-36 
31.10 

0.325 
0.258 

0.046 
0.032 

0.003 

0 

Lambeth  

Jan.  31.. 

JUnf.. 
(Filt'd. 

32.96 
32-74 

0.273 
0.258 

0.067 
0.038 

0.004 

O.OOI 

Grand  Junction     .        .  .      .       .  .      .    . 

Feb.  3.. 

JUnf.. 
1  Filt'd. 

31.42 
30.68 

0.262 
0.231 

0.042 
0.032 

0.004 

O.OOI 

Southwark,  Battersea.  

Feb.  5-. 

j  Unf.. 
1  Filt'd. 

31.80 
30.90 

0.239 
O.226 

0.047 
0.035 

0.005 

O.OOI 

West  Middlesex     

Feb.  7.. 

j  Unf.. 
I  Filt'd. 

31.22 
30.56 

0.209 
0.198 

0.071 
0.043 

0.005 

O.OOI 

RIVER  LEA. 

East  London                      ••              ••.... 

Feb.  i  .  . 

(  Unf.. 
|  Filt'd. 

34.680.3630.082 
34  700.3050.041 

I 

0.004 

O.OOI 

From  this  table  it  appears  that  the  filtration  effects  an  appre- 
ciable decrease  in  the  amount  of  organic  matter  as  judged  from 
the  "  organic  carbon "  and  "  organic  nitrogen."  In  ordinary 
practice  this  effect  is  trifling,  and  sand  filtration  is  not  sufficient 
to  remove  the  color  which  many  surface  waters  possess,  nor  to 
completely  remove  the  unpleasant  taste  which  sometimes  affects 
such  waters.  On  these  points  the  author  has  satisfied  himself  by 
abundant  experiments,  and  this  is  also  the  experience  at  Berlin. 
Here,  as  has  been  mentioned,  the  Spree  water  often  possesses  to 


RESULTS   OF  FILTRATION. 


161 


a  marked  degree  the  brownish-yellow  color  common  to  streams 
which  flow  through  marshy  or  peaty  regions,  and  to  the  water  of 
most  impounding  reservoirs.  This  color,  with  the  taste  which 
at  times  accompanies  it,  gives  rise  to  general  complaint,  but  even 
very  slow  filtration  fails  to  remove  it  to  any  considerable  extent. 
The  slight  action  which  has  been  observed  in  this  connection, 
Piefke,  resting  on  experiments  made  with  prepared  cellulose, 
ascribes  rather  to  the  sediment  containing  vegetable  fiber,  than 
to  the  sand  itself.  Table  XXIV  contains  the  results  of  a  few 
examinations  of  water  from  certain  American  localities :  here 
the  amount  of  organic  matter  is  indicated  by  the  "  albuminoid 
ammonia,"  and  this,  when  the  filter  beds  are  in  good  working  order, 
is  appreciably  less  in  the  filtered  than  in  the  unfiltered  water. 

TABLE  XXIV.  -"-EXAMINATION  OF  WATER  FROM  POUGHKEEPSIE  AND  HUDSON, 

N.  Y. 
[Results  expressed  in  Parts  in  100,000.] 


Q 
§ 

I 

LOCALITY. 

AMMONIA. 

"  ALBUMINOID  AM- 
MONIA." 

SOLID  RESIDUE. 

TOTAL  SOLIDS  AFTER 
FILTRATION  THROUGH 

PAPER. 

REMARKS. 

"  Organic 
and 

Volatile." 

Total  at 

2I2'1 

Fahr. 

l877. 

Nov.  13. 
Nov.  13, 

Nov.  19, 
Nov.  19, 

Nov.  27, 

Nov.  27, 

Dec.   10, 
Dec.  10, 

1878. 
Jan.  18, 

Jan.  18, 

POUGHKEEPSIE. 

0.0109 
0.0077 

0.0104 
O  OII2 

O.OO59 

o  .  0040 

0.0051 
0.0056 

0.0123 
0.0237 

0.0197 
0.0139 

0.0157 
0.0155 

0.0152 
0.0123 

0.0152 
0.0131 

0.0133 
0.0163 

i-7 
i.i 

i-5 
1-3 

1.  13 

12.  1 
9.I 

10.5 

9-4 

8.21 

10.  I 
9-0 

8.6 
9.0 

Very  turbid. 
Clear. 

Very  turbid. 
Slightly  turbid. 

Turbid. 
Slightly  turbid. 

Turbid. 
Slightly  turbid. 

Turbid. 
Slightly  turbid. 

Clear-water  basin  . 
River  

Clear-  water  basin. 
HUDSON. 
River 

Filtered  water.  .  .  . 
River    

0.72 

1.02 

1.  12 
0.92 

8.40 
8.14 

10.64 

II.  12 

IO.OO 
10.  60 

Filtered  water.  .  .  . 

Top  of  filter  bed, 
i.e.,  unfiltered.  . 
Filtered  water  .  .  . 

Sand  Filtration  in  f  the  United  States. 

Up  to  the  present  time  there  has  been  very  little  done  in  this 
country  in  the  way  of  systematic  filtration  of  water  supplies, 
partly,  perhaps,  from  indifference  and  lack  of  information,  but 


ii 


1  62  WATER  SUPPLY. 

mainly  on  account  of  the  expense.  The  numerous  complaints 
which  arise  in  the  case  of  almost  every  city  and  town  supplied 
with  surface  water  render  the  question  of  filtration  an  important 
one,  and  attempts  have  been  made  in  various  places  to  accom- 
plish the  desired  object  with  a  less  expensive  and  elaborate  plant 
than  that  required  by  the  English  system. 

Poughkeepsie,  on  the  Hudson  River,  in  the  State  of  New 
York,  was  the  first  city  in  the  Union  to  adopt  a  scheme  for 
the  artificial  filtration  of  the  entire  water  supply.  The  filtering 
works  consist  *  of  a  settling-basin  25  x  60  feet  in  plan  and  12  feet 
deep,  in  three  compartments,  arranged  with  reference  to  the 
deposition  of  the  heavier  particles  of  mud  before  the  water 
passes  on  to  the  beds.  The  two  filter  beds  are  each  200  by  73! 
feet  in  planT  and  12  feet  deep,  built  with  vertical  walls  ;  each  has, 
therefore,  14,700  square  feet  of  filtering  area.  The  6  feet  of 
filtering  materials,  beginning  at  the  top  of  the  bed,  are  disposed 
as  follows  : 

24  inches  of  sand. 
6     "        "  \  inch  gravel. 


6     "        "2      '    broken  stone. 
24     "        "  4  to  8  in.     "       " 

Total,  72  inches. 

The  beds  have  a  concrete  bottom  or  floor  12  inches  in  thick- 
ness, upon  which  are  arranged  open  stone  culverts  to  conduct  the 
filtered  water  to  the  intermediate  basin.  The  flow  of  water  from 
each  bed  to  this  intermediate  basin  is  controlled  by  a  gate,  so 
that  while  one  bed  is  being  cleaned  the  other  may  be  used.  The 
filtration  is  conducted  in  the  usual  manner,  as  is  also  the  clean- 
ing and  renewal  of  the  sand,  an  inch  or  so  of  sand  being  removed 
at  a  time,  and  the  sand  being  washed  and  replaced  only  when 
the  upper  layer  has  been  much  reduced  in  thickness. 

The  intermediate  filtered-water  basin  is  6x85  feet  in  plan, 
and  16  feet  deep.  This  retains  the  filtered  water  until  it  is 
allowed  to  pass  into  the  filtered-water  reservoir.  This  reservoir 
is  28  x  88  feet  in  plan,  and  17  feet  deep,  and  from  it  the  water  is 
pumped  to  the  uncovered  distributing  reservoir  from  which  the 

*  See  Fourth  Annual  Report  of  the  Water  Commissioners  of  the  City  of  Pough- 
keepsie for  the  year  ending  Dec.  31,  1872. 


COVERED   FILTER  BEDS.  163 

service  pipes  are  fed.  Sluice  gates  and  drain  pipes  permit  the 
lowering  of  the  water  on  the  beds  in  any  or  all  of  the  basins. 

The  city  of  Hudson,  N.  Y.,  is  also  supplied  from  the  Hudson 
River.  The  river  water  is  pumped  to  the  summit  of  a  hiil  over- 
looking the  town,  on  which  are  situated  the  filter  bed  and  the 
distributing  reservoir.  The  filter  basin  *  is  13^  feet  in  depth,  is 
built  with  sloping  sides,  and  has  an  area,  at  the  surface  of  the 
sand,  of  9,081  feet. 

The  filtering  material  is  six  feet  deep,  and  is  arranged  pre- 
cisely as  in  the  Poughkeepsie  works  which  have  been  already 
described.  The  fragments  of  broken  stone  rest  upon  a  concrete 
floor  six  inches  in  thickness,  having  a  slight  inclination  toward 
the  middle  or  axial  line,  and  this  line  toward  the  outlet.  Along 
this  line  runs  an  openly-laid  stone  culvert  18x24  inches,  which  is 
connected  by  a  cast-iron  pipe  under  the  division  embankment 
with  the  clear-water  well.  From  the  clear-water  well  the  filtered 
water  passes  over  a  gate  or  weir,  where  it  is  measured  and  its 
flow  regulated,  to  the  clear-water  basin  or  distributing  reservoir. 
Thence  it  passes  ordinarily  into  the  effluent  chamber  through 
fine  copper-wire  screens  to  the  1 8-inch  supply  pipe  ;  but  the 
clear-water  well  can  be  connected  directly  with  the  supply  main, 
so  that  the  city  may  be  supplied  from  the  bed  without  passing 
the  water  through  the  basin  or  distributing  reservoir.  The  dis- 
tributing reservoir  is  20  feet  deep  ;  its  capacity  is  3,200,000  gal- 
lons. Chemical  examinations  of  the  water  from  these  localities 
have  been  given  in  Table  XXIV. 

Advantages  of  Covered  Filter  Beds. 

The  exposure  of  a  comparatively  thin  layer  of  water  on  the 
surface  of  the  filter  beds  has  at  least  two  disadvantages.  In  the 
first  place,  in  summer  the  water  becomes  heated  and  is,  conse- 
quently, in  a  condition  to  favor  the  growth  of  the  lower  orders 
of  plant  life ;  in  the  second  place,  in  winter  there  is  likely  to  be 
inconvenience  from  the  freezing  of  the  water.  In  the  climate  of 
England  neither  of  these  difficulties  is  as  serious  as  in  countries 
which  are  either  much  warmer  or  much  colder,  and  the  filter 
beds  are  universally  uncovered.  On  the  Continent,  however, 

*  See  Third  Report  of  the  Water  Commissioners  of  the  City  of  Hudson,  1875. 


164  WATER   SUPPLY. 

the  beds  and  the  clear-water  reservoirs  are  sometimes  covered  as 
at  Berlin,  Magdeburg  and  other  places.  With  reference  to  the 
first  point — vegetable  growth — some  trouble  is  experienced  even 
in  England,  and  the  beds  become  clogged  with  a  confervoid 
growth,  which  forms,  as  it  were,  a  «*ort  of  carpet  on  the  surface 
of  the  sand,  and  this,  when  the  beds  are  cleaned,  can  be  raked 
off  or  rolled  up  in  a  coherent  sheet.  This  trouble  might  be 
lessened  somewhat  by  the  use  of  covered  beds,  but  where  the 
water  to  be  filtered  contains  an  abundance  of  minute  algae,  as  is 
the  case  with  the  water  of  the  Spree,  at  Berlin,  there  is  no 
perceptible  difference  in  the  condition  of  the  covered  and  un- 
covered beds. 

With  reference  to  the  second  point  alluded  to  above — the 
freezing  of  the  water  in  winter — the  European  practice,  in  loca- 
tions where  the  ice  freezes  to  any  thickness,  may  be  learned  by 
the  following  quotation  from  Kirkwood's  account  of  the  Berlin 
works :  "  The  long  and  severe  winters  here  made  special  care 
and  precaution  necessary  in  the  use  of  filters  during  the  months 
of  severe  frost.  The  filter  beds  cannot  be  laid  bare  in  mid- 
winter; for  the  frost  would  in  that  case  penetrate  the  body  of 
the  filter  and  render  it  useless.  All  the  filters  are,  in  conse- 
quence, during  the  winter  months,  kept  constantly  covered  with 
their  maximum  depth  of  water,  four  feet.  Luckily  the  river 
water  during  the  winter  months  is  in  its  best  state  as  regards 
freedom  from  turbidity,  and  also  as  regards  freedom  from  vege- 
table discoloration  or  impurity.  The  filters,  therefore,  have 
comparatively  little  to  intercept,  and  the  river  water  is  flowed 
continuously  upon  them,  and  passes  through  them  without 
very  sensibly  impairing  their  efficiency.  To  make  provision, 
however,  for  an  unusually  long  winter,  or  for  an  exceptional 
condition  of  the  river  then,  which  may  occasionally  occur,  it  is 
evident  that  a  larger  filtering  surface  is  desirable  than  would  be 
necessary  in  a  milder  climate. 

"The  ice  forms  upon  the  filter  beds  15  inches  thick,  and 
sometimes,  though  rarely,  24  inches  thick.  To  protect  the  en- 
closing walls  of  each  filter  from  damage,  the  ice  is  kept  separated 
from  the  walls,  6  to  12  inches,  by  attendants  appointed  to  that 
duty ;  and,  so  long  as  the  cake  of  ice  is  kept  floating  in  this  way, 
the  masonry  is  safe  from  any  danger  by  its  thrust.  That  this 
service  has  been  well  performed,  is  demonstrated  by  the  condi- 


FILTRATION   IN   WINTER.  165 

tion  of  the  walls,  which  are  in  the  best  of  order,  and  nowhere 
out  of  line,  or  abraded,  that  I  could  perceive." 

Since  the  date  of  Mr.  Kirkwood's  report,  covered  filter 
beds  have  been  built,  and  it  is  stated  that  the  uncovered  beds 
are  not  cleaned  during  the  winter,  the  burden  of  the  work 
being  thrown  upon  the  covered  beds.  At  Poughkeepsie  and 
at  Hudson,  the  filtering  area  is  not  sufficient  to  deliver  the 
water  throughout  the  winter  without  occasional  cleaning.  The 
ice  has  therefore  to  be  broken  up  and  thrown,  or  rather,  dragged 
out. 

There  is  no  question  but  that  water  once  filtered-  should  be 
distributed  as  soon  as  possible  to  the  consumers.  If  it  is  neces- 
sary that  the  water  should  be  stored,  it  should  be  in  covered 
reservoirs  of  small  size,  which  can  be  readily  emptied  and  cleaned 
in  case  of  necessity.  Apparently,  the  spores  of  certain  algae  are 
not  removed  by  filtration:  at  any  rate,  it  has  been  found  that  if, 
after  filtration,  the  perfectly  clear  Spree  water  is  allowed  to 
stand  for  eight  or  ten  days,  algae  are  developed.  This  fact  is  of 
no  practical  consequence  in  a  case  like  that  of  Berlin,  where  the 
clear-water  reservoir  is  too  small  to  hold  a  single  day's  consump- 
tion, and  where,  consequently,  the  water  is  delivered  at  once 
into  the  service  mains. 

Expense  of  Sand  Filtration. 

The  most  valuable  accessible  data  of  the  expense  of  filtration, 
as  drawn  from  actual  experience,  are  found  in  the  reports  of  the 
Poughkeepsie  Water  Works.  From  these  data  it  seems  that  the 
expense  may  be  set  at  from  $2.50  to  $3.50  per  million  gallons, 
not  allowing  for  the  interest  on  the  plant  or  for  the  cost  of  pump- 
ing. The  original  cost  of  the  beds  was  §54,000,  the  interest  on 
which  would  exceed  the  cost  of  maintenance.  In  1879,  Mr.  J. 
P.  Davis,  City  Engineer  of  Boston,  Mass.,  estimated  the  cost  of 
constructing  and  operating  artificial  filters  for  the  Mystic  water 
supply  of  the  city— 10,000,000  gallons  daily.  He  allowed  for 
seven  beds,  each  with  an  area  of  33,000  square  feet,  and  esti- 
mated that  the  cost  of  pumping  and  of  operating  the  filters  would 
be  about  $5  per  million  gallons,  and  the  interest  on  the  neces- 
sary works,  at  five  per  cent,  would  be  nearly  §6.00  per  million 
gallons,  making  the  total  cost  about  §11.00. 


1 66  WATER   SUPPLY. 

Filtering  Materials  other  than  Sand. 

Many  other  substances  have  been  proposed  from  time  to 
time  as  suitable  to  replace  the  sand  wholly  or  in  part,  and  to 
accomplish  more  than  sand  can  by  chemical  action  on  the  impu- 
rities of  the  water  filtered.  The  so-called  carbide  of  iron,  of  Mr. 
Thomas  Spencer,  is  used  in  several  towns  of  England  with  some 
success.  The  carbide  of  iron  is  prepared  by  roasting  a  mixture 
of  hematite  iron  ore  and  sawdust,  and  is  held  to  consist  mainly 
of  the  magnetic  oxide  of  iron  :  it  is,  no  doubt,  an  efficient  puri- 
fying agent.  It  is,  however,  expensive,  and  could  hardly  be  pre- 
pared for  less  than  $20  or  $25  per  ton,  and  for  the  best  effect 
should  be  preceded  by  a  rough  sand  filtration.  At  Wakefield, 
England,  where,  to  be  sure,  the  water  is  extremely  filthy,  and 
the  bed  confessedly  overworked,  the  Rivers  Pollution  Commis- 
sion found  that  "  the  water,  owing  in  part  to  putrescent  fermen- 
tation and  subsidence,  and  in  part  to  filtration,  was  chemically  less 
contaminated  than  might  be  expected,  yet  on  both  occasions  it 
contained  a  large  proportion  of  nitrogenous  organic  matter.  It 
was  of  a  greenish-yellow  color,  and  on  one  occasion  very  turbid." 

Various  attempts  have  been  made  to  use  iron  as  a  filtering 
medium  since  Medlock,  in  1857,  patented  the  process  for  purify- 
ing water  by  allowing  it  to  stand  for  some  time  in  contact  with  a 
considerable  quantity  of  metallic  iron.  It  is  claimed  that  "  spongy 
iron  "  is  now  being  used  with  success  at  Antwerp.*  This  mate- 
rial, which  was  introduced  as  a  medium  for  household  filters  a 
few  years  ago  by  Prof.  Bischof,  is  prepared  by  reducing  hema- 
tite ore,  and  is  in  a  peculiarly  porous  or  spongy  condition.  The 
filters  at  Antwerp  are  said  to  have  been  laid  out  to  treat  over 
two  million  gallons  per  day,  but  it  does  not  appear  that  anything 
like  that  amount  is  yet  treated.  The  works  went  into  operation 
in  June,  1881,  and  after  twelve  months  Dr.  Frankland  was  re- 
quested to  examine  and  report  on  them.  The  following  is  taken 
from  his  report  : 

"  The  water,  which  was  abstracted  from  the  river  Nethe,  about 
fifteen  miles  above  Antwerp,  is  first  impounded  in  two  reservoirs, 
where  it  is  allowed  to  subside  for  from  12  to  24  hours  ;  from  these 
reservoirs  it  is  pumped  on  to  the  spongy  iron  filters,  whence  it 
flows  by  gravitation  upon  sand  filters. 

*  Circular  of  "  The  Spongy  Iron  Water  and  Sewage  Purifying  Company,"  London. 


FILTRATION  THROUGH   SPONGY  IRON.  167 

"  The  spongy  iron  filters  consist  of  two  layers  of  bricks  loosely 
laid  upon  a  bed  of  concrete.  On  the  bricks  rests  a  layer  3  feet 
in  thickness,  formed  of  5  m.m.  gravel  mixed  with  one-third  of 
its  bulk  of  spongy  iron.  Then  comes  a  layer  3  inches  thick  of 
fine  gravel,  and  lastly  a  stratum  of  sand  2  feet  deep,  making  in 
all  5  feet  3  inches  of  filtering  material. 

"  The  sand  filters  are  similarly  laid  upon  bricks  and  concrete. 
They  consist  of  a  layer  of  5  m.m.  gravel  I  foot  thick,  covered 
with  3  inches  of  fine  gravel  and  topped  with  2  feet  6  inches  of 
sand,  making  altogether  3  feet  9  inches  of  filtering  material. 

"  The  area  of  filtering  surface  of  each  filter  amounts  to  7,302 
square  feet,  and  the  rate  of  filtration  varies  from  300  to  500 
gallons  per  minute,  or  from  60  to  100  (imp.)  gallons  per  square 
foot  per  24  hours. 

"  The  result  of  the  analysis  of  the  three  samples  of  water 
show  that  even  after  subsidence  for  nearly  24  hours,  the  water 
of  the  Nethe  is  exceedingly  impure,  being  still  turbid  and  loaded 
with  an  unusually  large  proportion  of  highly  nitrogenized  organic 
matter.  The  composition  of  the  water  as  it  passed  on  to  the 
spongy  iron  filters  is  stated  to  have  been : 

Total  solids  (mostly  dissolved) 21  parts  in  100,000, 

Organic  Carbon 0.623 

Organic  Nitrogen 0.219 

Ammonia o  028 

Chlorine  (combined) 1.8 

Hardness — temporary 4.6° 

permanent 6. 9° 

"  total 11.5° 

The  water  in  this  condition  was  very  unpalatable. 

"The  aggregate  effect  produced  by  one  filtration  through 
spongy  iron  was  as  follows : 

Total  percentage  reduction. 

Total  solids 41.3 

Organic  carbon 60.9 

Organic  nitrogen 74.9 

Ammonia 

Total  combined  nitrogen 77.3 

Chlorine o. 

Temporary  hardness 13.0 

Permanent         "       35.3 

Total  "       27.0 


1 68  WATER  SUPPLY. 

"  The  nitrogenous  character  of  the  organic  matter  was  dimin- 
ished from  the  initial  proportion,  nitrogen  to  carbon  =  I  :  2.84, 
down  to  i  :  4.4.  By  boiling,  the  hardness  of  the  doubly  filtered 
water  is  reduced  to  4.4  parts  per  100,000,  or  3°  on  Clark's  scale. 

"  Lastly,  from  being  muddy,  unpalatable,  colored  and  much 
polluted,  the  water  of  the  Nethe  was  rendered  colorless,  bright, 
palatable  and  fit  for  dietetic  and  domestic  purposes." 

Wood-charcoal  is  often  used  in  filters  of  small  size,  mixed 
with  sand.  Practically,  however,  it  adds  nothing  to  the  efficiency 
of  a  properly  managed  sand  filter.  One  way  in  which  charcoal 
is  used  is  illustrated  by  the  works  of  Marshalltown,  Iowa.  Here 
a  filter  basin,  32  X  16  feet,  was  built  of  masonry ;  and  a  filter  floor 
of  two-inch  plank  was  supported  on  joists  laid  crosswise.  The 
floor  was  pierced  with  three-fourth  inch  holes,  and  covered  with 
wire  gauze.  On  this  there  is  a  layer  of  charcoal  four  inches  thick, 
and  above  this  14  inches  of  clean  gravel  and  sand.  At  Clinton, 
Iowa,  a  number  of  boxes,  16  in  fact,  filled  with  charcoal,  gravel, 
and  sharp  sand,  rest  upon  the  conduit.  The  water  flows  on  to 
the  boxes,  and  through  the  material  into  the  conduit.  The  boxes 
can  be  raised  one  at  a  time  for  cleaning.  In  case  of  fire,  how- 
ever, the  water  is  taken  into  the  conduit  without  filtration. 
Sponge,  which  is  much  used  in  filtering  water  for  manufacturing 
operations,  such  as  paper-making,  has  been  used  to  a  limited  ex- 
tent in  connection  with  sand  and  gravel,  even  on  the  larger  scale 
of  a  town  supply.  Alton,  111.,  pumps  from  the  Mississippi  River; 
and  the  water  is  filtered  through  sponge  contained  in  a  cast-iron 
filter  box  of  54  cubic  feet  capacity  :  this  box  fits  into  a  tight 
chamber  in  the  aqueduct  leading  from  the  river  to  the  pump- 
well,  and  can  be  raised  by  machinery.  The  box  can  be  raised, 
the  sponges  renewed,  and  the  box  replaced,  in  three  hours.  The 
amount  of  water  filtered  is  about  150,000  gallons  a  day.  When 
the  river  is  muddy  the  sponges  are  cleaned  every  three  or  four 
weeks :  sometimes,  when  the  river  is  clear,  not  oftener  than  once 
in  three  months.  An  attempt  was  made  at  one  time  to  filter  the 
supply  of  the  village  of  Malone,  N.  Y.,  through  a  filter  of  soft 
brick,  but  it  was  not  found  practicable  to  filter  with  sufficient 
rapidity. 

Many  other  water  works,  in  this  country,  make  some  attempt 
to  "  filter  "  their  water  by  passing  it  through  broken  stone,  gravel, 
or  gravel  and  charcoal,  or  even  through  sand  and  gravel.  In 


HOUSEHOLD   FILTRATION.  169 

general,  the  most  that  can  be  said  of  these  arrangements  is  that 
they  act  with  greater  or  less  efficiency  as  strainers,  removing 
some  of  the  coarser  matters  ;  the  infrequency  of  the  cleansing 
showing  that  the  work  done  cannot  be  very  great.  As  an  illus- 
tration of  this  point,  may  be  mentioned  a  locality  where  the  filter 
beds  were  constructed  as  long  ago  as  1853.  They  are  built  with 
sloping  sides  and  measure  50x60  feet.  The  filtering  material, 
which  consists  of  sand,  gravel,  and  pebble  stones,  has  an  entire 
thickness  of  24  inches,  and  filtration  is  carried  on  under  a  head 
of  from  10  to  15  feet.  The  beds  are  not  used  in  winter,  but  when 
in  use  the  amount  of  water  filtered  daily  is  1,500,000  gallons. 
The  beds  are  cleaned  not  oftener  than  once  a  year.  This  is  an 
extreme  case,  but  inadequate  area  and  infrequent  cleansing  are 
the  common  faults  of  many  so-called  filters.  Of  course,  occa- 
sionally, the  character  of  the  suspended  matter  which  is  to  be  re- 
moved is  such  that  a  very  simple  straining  process  is  all  that  is 
required :  this  is  the  case  with  some  of  our  streams  on  which  are 
a  number  of  saw-mills,  and  where  the  comparatively  coarse  par- 
ticles of  sawdust  comprise  the  main  part  of  the  impurity.  In 
such  a  case,  as,  for  instance,  at  Eangor,  Me.,  simple  passage 
through  a  limited  amount  of  sand  is  all  sufficient. 

Household  Filtration. 

In  localities  where  there  is  a  public  water  supply,  it  is,  with- 
out doubt,  the  duty  of  the  water  board  or  company  to  deliver 
the  water  to  consumers  in  a  condition  fit  for  domestic  use.  If 
the  source  which  is,  on  the  whole,  the  most  available  for  the 
water  supply  is  such  that  filtration  is  absolutely  necessary,  the 
water  should  be  filtered  on  the  large  scale  by  the  authority  con- 
trolling the  works.  Practically,  however,  in  the  case  of  most 
existing  water  supplies,  the  water  as  delivered  to  the  consumers 
may  be  appreciably  improved  by  filtration  ;  household  filtration 
is  also  often  necessary  in  country  residences  and  in  the  smaller 
towns  where  there  is  no  public  supply,  and  where  it  is  necessary 
to  use  rain  water  which  has  been  stored  in  tanks  or  cisterns. 

For  filtration  on  the  household  scale,  numerous  devices  have 
been  made  and  patented,  and  the  greatest  variety  of  material 
has  been  proposed  :  many  sorts  of  porous  stone,  sand,  powdered 
glass,  bricks,  iron  in  turnings  and  other  forms,  vegetable  and 
animal  charcoal,  sponge,  wool,  flannel,  cotton,  straw,  sawdust, 


I/O  WATER   SUPPLY. 

excelsior  and  wire-gauze — these  are  some  of  the  substances 
which  are  used.  A  filter  suitable  for  household  use  must  be 
made  of  a  material  which  cannot  communicate  any  injurious  or 
offensive  quality  to  the  water  which  passes  through  it ;  it  must 
remove  from  the  water  all  suspended  particles,  so  as  to  render 
the  water  bright  and  clear;  and  it  must  either  be  readily  cleaned, 
or  the  filtering  material  must  be  such  as  to  be  readily  renewed. 
In  addition  to  these  requirements,  it  is  of  great  advantage  if  the 
filter  is  able  to  remove  a  noticeable  amount  of  the  dissolved 
organic  matter  which  most  waters  contain. 

As  to  the  filtering  material,  the  author*  is  satisfied  that 
there  is  nothing,  on  the  whole,  better  than  well-burned  animal 
charcoal  (bone-coal).  This  material,  as  is  well  known,  possesses 
great  power  in  removing  organic  matter  from  solution,  and  is 
used  in  the  arts  to  decolorize  colored  solutions  :  on  many  organic 
substances  it  acts,  not  simply  by  adhesion,  but  apparently  by 
bringing  them  into  contact  with  oxygen,  and  thus  absolutely 
destroying  them.  Its  power  does  not  last  indefinitely,  and  a 
bone-coal  filter,  like  a  filter  of  any  other  material,  requires  cleans- 
ing and  renewal  at  proper  intervals.  Other  materials  to  be 
mentioned  render  good  service,  and  in  certain  sorts  of  filters, 
as,  for  instance,  those  made  for  attachment  to  ordinary  cocks 
or  faucets,  the  bone-coal  possesses  no  essential  advantage. 

We  will  consider  first  the  filters  of  small  size,  intended  to 
be  attached  to  the  faucet,  where  the  water  is  brought  in  pipes 
either  from  the  service-mains  of  a  general  supply,  or  from  a 
tank  in  the  building ;  second,  the  portable  filters  intended  to 
occupy  a  more  or  less  permanent  position,  and  to  be  filled  with 
water,  either  by  some  ball-cock  or  other  similar  arrangement, 
or  by  means  of  smaller  supplies  continually  renewed  ;  third, 
the  more  permanent  and  fixed  devices  which  are  inserted  or 
built  into  underground  and  other  cisterns,  or  are  introduced 
into  the  course  of  the  service-pipes  so  that  all  the  water  used 
in  the  house  passes  through  them. 

Considering  the  volume  of  water  which  must  flow  through 
an  extremely  limited  amount  of  material,  no  filter  capable  of 
being  screwed  on  to  an  ordinary  water-tap  can  act  in  any  other 
way  than  as  a  strainer,  and  all  that  can  be  required  of  such  a 
filter  is  that  it  shall  remove  suspended  particles  and  be  readily 

*  See  Nichols  :  Filtration  of  Potable  Water.    New  York,  Van  Nostrand. 


HOUSEHOLD   FILTRATION.  17 1 

cleansed  or  renewed  at  trifling  expense.  The  older  forms  of 
filters,  which  could  be  cleaned  only  by  unscrewing  from  the 
tap  and  reversing  either  the  whole  apparatus  or  some  inside 
receptacle  of  the  filtering  medium,  were  all  open  to  objection, 
and  no  one  of  them  was  to  be  recommended  as  superior  to 
the  primitive  and  unpatentable  device  of  attaching  to  the  faucet 
a  bag  of  cotton- 
flannel  to  be  fre- 
quently washed 
and  renewed.  At 
present,  however, 
there  are  certain 
forms  of  filter  in 
the  market  which 
can  be  reversed 
without  removing 
them  from  the  tap, 
and  which  are  su- 
perior to  anything 
previously  in  use 
for  the  purpose. 
Figure  32  shows 
such  a  filter.  The 
water  passes 

through  the  wire 

„  FIG.  32. 

gauze    at   E   and 

the  filtering  material  F.  By  means  of  a  handle,  the  stem  of  which 
is  shown  in  the  figure,  the  ball  may  be  turned  over  and  the  sedi- 
ment collected  on  E  be  carried  away  with  the  first  rush  of  water. 
By  turning  the  handle  half  way,  water  may  be  drawn  directly 
without  passing  through  the  filtering-ball. 

We  come  now  to  the  larger  forms  of  filters,  to  those  which 
are  portable,  but  which  are  intended  to  occupy  a  permanent 
position  in  the  room,  or  in  some  cases  to  be  placed  in  the  tank 
from  which  the  supply  is  drawn.  The  material  which,  next  to 
simple  sand,  has  probably  been  used  as  long  as  anything  for  the 
purpose,  is  stone.  Some  varieties  of  sandstone  are  particularly 
porous,  sufficiently  so  to  allow  of  the  use  of  slabs  of  the  stone 
as  filters  ;  other  similar  substances,  such  as  pumice  stone  or 
unglazed  earthenware,  have  been  employed  ;  the  most  common 


172 


WATER   SUPPLY. 


arrangement  being  to  insert  the  stone  as  a  horizontal  partition 
in  a  small  tank  or  vessel :  the  action  is,  in  the  main,  mechanical, 
and  the  sediment  which  collects  upon  the  upper  surface  of  the 
block  is  removed  by  washing  and  brushing.  A  material  which 
is  used  to  a  considerable  extent  in  England  is  the  so-called  sili- 
cated  carbon  :  it  is  the  residue  of  the  distillation  of  a  certain 
variety  of  bituminous  shale.  Thus  it  is  a  coke  mixed  with  min- 
eral matter,  and  is  compressed  into  blocks  for  use.  In  the  com- 
mon form  of  household  filters  of  this  make,  the  block  is  cemented 
as  a  partition  into  an  earthen  jar,  and  is  not  readily  cleaned,  but 
there  is  no  doubt  that,  until  the  filter  becomes  clogged,  it  is 
very  efficient  in  purifying  water  even  from  the  dissolved  organic 

matter. 

As  a  type  of  the  better 
class  of  tank  filters,  we  may 
take  that  much  employed  in 
England  and  manufactured 
by  the  London  and  General 
Water  Purifying  Company ; 
this  filter*  is  shown  in  ele- 
vation and  in  section  in  Figs. 
33  and  34.  The  earthenware 


FIG.  33. 


filter  box  is  filled  with  ani- 
mal charcoal,  in  the  form  of 
charred  bones,  broken  into  small  pieces,  and  freed  from  dust. 
There  is  no  chamber  for  storing  filtered  water :  the  water  is 
filtered  at  the  time  it  is  drawn  off  for  use.  The  filter  is  readily 
cleansed  and  the  charcoal  re- 
newed. The  water  passes 
upward  through  the  filtering 
material,  in  order  that  mat- 
ters spontaneously  settling 
down  may  not  be  deposited 
upon  the  filtering  material, 
and  may  not,  therefore,  help 
to  clog  its  pores ;  and,  fur- 
ther, that  the  suspended 
matters  strained  from  the 
water,  being  separated  as  they 


FIG.  34. 


A  very  similar  filter  made  in  Boston,  England,  is  on  sale  in  this  country. 


HOUSEHOLD   FILTRATION. 


173 


always  are,  mainly  at  the  surface  of  the  filtering  material,  may 
fall  away  from  it  and  deposit  elsewhere  ;  the  consequence  of  this 
is,  that  the  filtering  material  requires  less  frequent  cleansing. 

Bone  coal  is  also  used  compressed  into  cylindrical  blocks 
with  an  aperture  in  the  center  into 
which  the  delivery  pipe  is  inserted, 
and  one  or  more  of  these  may  be 
placed  in  the  tank  from  which  the 
water  is  taken.  As  a  rule,  the  pre- 
viously described  method  of  using 
the  bone  coal  is  to  be  preferred. 

Another  material  which  has  late- 
ly come  into  use  to  a  considerable 
extent  in  England,  is  what  is  known 
as  "  spongy  iron,"  which  has  already 
been  alluded  to  in  the  description 
of  the  filtration  works  at  Antwerp. 
The  portable  filters  are  constructed 
in  various  forms,  but  on  the  same 
general  plan.  Fig.  35  represents 
one  form,  where  the  water  is  sup- 
plied from  an  inverted  bottle,  which 
must  be  refilled  as  often  as  empty. 
In  other  forms  the  reservoir  of  un- 
filtered  water  is  kept  full  by  being 
connected  with  the  service  pipe  by 
means  of  a  ball-cock  attachment. 
The  vessels  are  of  earthenware,  but 
the  spongy  iron  is  also  furnished  in 
filters  which  can  be  inserted  in  tanks 
or  cisterns. 

Although,  at  any  rate  with  the 
smaller  forms  of  filter,  it  is  difficult 
or  impossible  to  obtain  a  water  free  from  iron,  there  is  no  doubt 
that  a  considerable  portion  of  the  dissolved  organic  matter  is 
removed,  and  it  is  claimed  that  bacteria  and  bacterial  germs  are 
completely  removed.  These  claims  are  borne  out  by  the  experi- 
mental investigations  of  Bischof,*  Hatton,f  and  others,  and  give 


FIG.  35- 


*  Proc.  Roy.  Soc.,  xxvii,  p.  258.     . 
f  Journ.  Chem.  Soc.,  xxxix,  p.  247. 


WATER   SUPPLY. 

to  the  material  a  great  theoretical  advantage.  Practically,  how- 
ever, it  is  extremely  doubtful  whether  in  the  ordinary  use  of  the 
spongy  iron  in  filters  such  results  can  be  obtained  ;  and  at  the 
best,  the  water  must  pass  very  slowly  through  the  filter  in  order 
that  purification  may  take  place.  Like  other  materials  used  for 
the  purpose,  it  affords  a  means  for  improving  an  undesirable 
water,  and  for  lessening  the  risk  in  using  a  doubtful  water :  it 
does  not  afford  an  excuse  for  employing  a  water  known  to  be 
impure,  on  the  ground  that  possible  danger  will  thus  be  certainly 
averted. 

Wood-charcoal  is  sometimes  used  in  household  filters,  but, 
practically,  it  has  next  to  no  chemical  action.  The  author  had 
occasion  some  time  since  to  examine  an  American  filter  which  is 
much  used  in  certain  sections  of  the  country,  and  in  which  the 
filtering  medium  is  wood-charcoal  with  clean  quartz  pebbles. 
The  filtering  material  is  arranged  in  an  oak  tub  and  the  water  is 
placed  in  a  zinc  pan  at  the  top,  and  passes  first  through  a  hand- 
ful of  sponge  and  then  downward  through  the  pebbles  and  char- 
coal. The  experiments  extended  over  several  months,  and  the 
water  was  examined  by  Frankland's  and  by  Wanklyn's  method. 
In  the  case  of  the  Boston  water,  when  the  filter  was  in  constant 
use,  absolutely  no  effect  was  produced  on  the  water — the  water 
which  issued  from  the  filter  containing  exactly  the  same  amount 
of  organic  matter  as  when  it  entered.  If  the  sponge  were  taken 
out,  thoroughly  washed  and  replaced,  there  was  for  a  short  time 
a  slight  difference  between  the  filtered  and  unfiltered  water,  but 
the  effect  was  temporary  and  soon  ceased.  In  spite  of  the  bulk 
and  weight  of  this  filter  (the  smallest  size  of  which  weighs  about 
150  Ibs.),  the  entire  work  with  water  of  this  character  seems  to 
be  done  by  the  handful  of  sponge  at  the  top.  The  filter  is  one 
of  a  class  which  claim  to  be  chemical  in  their  action,  but  which 
cannot  do  more  than  remove  suspended  matter ;  and  the  action 
on  clayey  waters,  with  which  the  filter  is  sometimes  used  to  ad- 
vantage, is  probably  largely  due  to  the  principle  illustrated  on 
page  153  (Fig.  30). 

The  following  simple  form  of  filter  is  described  by  Dr.  Smart, 
and  answers  fully  as  well  as  many  patented  contrivances.  "  The 
filter  is  made  of  tin  and  consists  of  a  modified  funnel,  the  body 
of  which  rests  on  a  tin  bucket  or  receiver,  while  the  tube  projects 
downward  to  the  bottom  of  the  said  bucket.  The  lower  end  of 


HOUSEHOLD   FILTRATION.  175 

the  tube  is  tied  over  with  some  filtering  cloth.  Three-fourths  of 
its  length  is  filled  with  granulated  bone  charcoal  and  the  upper 
fourth  with  sand.  The  upper  end  of  the  tube  projects  about  half 
an  inch  into  the  body  of  the  funnel  to  permit  of  tying  a  filtering 
cloth  over  the  top  of  the  sand.  The  angle  between  this  projec- 
tion and  the  sloping  sides  of  the  funnel  will  serve  to  trap  solid 
matter.  To  clean  this  filter,  the  filtering  cloth  guarding  the  top 
of  the  tube  will  have  to  be  removed,  washed,  and  replaced.  At 
longer  intervals,  when  the  filter  shows  signs  of  clogging,  half  an 
inch  of  the  upper  layer  of  sand  may  be  removed  and  replaced  by 
fresh  material.  At  yet  longer  periods,  depending  upon  the  length 
of  time  during  which  the  charcoal  retains  its  powers  of  oxidation, 
the  whole  contents  of  the  tube  may  be  dumped  out  and  re- 
newed. Earthenware  is  more  durable  than  tin,  and  would  pre- 
serve the  water  cooler  during  the  warm  months." 

There  are  various  filters  in  the  market  which  are  arranged  for 
use  where  there  is  a  public  water  supply,  by  being  connected  with 
the  service  pipes  in  such  a  way  that  all  the  water  entering  the 
building  passes  through  the  filter.  By  proper  arrangement  of 
valves  it  is  possible  to  reverse  the  current  and  cleanse  the  filter 
from  the  collected  impurities.  In  some  cases  the  valves  are  so 
arranged  that  the  filter  can  be  cleaned  by  a  reverse  current  of 
hot  water  or  steam.  The  revolving  filters,  mentioned  on  page 
171  as  adapted  to  faucets,  are  also  made  on  the  larger  scale  for 
insertion  in  the  service-pipes  of  houses  and  other  buildings  and 
for  manufacturers'  use. 

We  come  now  to  the  discussion  of  filters  suitable  for  cisterns 
of  considerable  size,  and  especially  for  the  underground  cisterns 
in  which  rain  water  is  usually  stored.  The  collection  of  water 
from  the  roofs  of  houses  involves  the  collection  of  dust  and  dirt 
more  or  less  objectionable  in  character,  especially  in  places  where 
soft  coal  is  burned.  Although  it  is  possible  by  automatic  con- 
trivances to  avoid  the  collection  of  the  first  portions  of  the  water 
coming  at  any  time  from  the  roof,  yet  these  do  not  perfectly  ac- 
complish their  intended  object,  and  are  not  at  all  commonly  em- 
ployed. Moreover,  the  construction  of  ordinary  cisterns  is  such 
that,  after  the  water  is  once  collected,  it  is  liable  to  deterioration 
and  to  contamination  by  various  foreign  matters  which  fall  into 
it,  so  that,  if  not  absolutely  necessary,  filtration  is  certainly  very 
desirable.  Where  the  water  is  stored  in  tanks  in  the  roof  of  the 


1/  WATER  SUPPLY. 

building,  one  of  the  various  forms  of  filters  just  alluded  to  may 
be  placed  beneath  the  tank  and  so  connected  that  ail  the  water 
used  shall  pass  through  it.  The  outlet  pipe  from  the  tank  should 
start  several  inches  from  the  bottom,  in  order  that  the  sediment 
may  deposit  itself  as  far  as  possible  on  the  floor  of  the  tank  and 
not  be  drawn  into  the  filter:  the  tank  should,  of  course,  be 
cleaned  from  time  to  time.  The  disadvantage  of  this  method  is 
the  inability  to  command  a  sufficient  head  of  water  to  properly 
clean  the  filter  by  reversing  the  current.  The  tank  may  be 
divided  by  a  partition  and  the  water  be  required  to  pass  through 
a  filter  constructed  in  the  tank  itself  and  filled  with  sand  and 
charcoal  or  bone-coal,  or  one  of  the  patent  tank  filters  already 
described  may  be  employed.  (See  Figs.  33  and  34.) 

With  underground  cisterns,  it  is  not  uncommon  to  construct 

them  so  that  the  water  is  not 
pumped  directly  from  the  cis- 
tern, but  from  a  sort  of  pump- 
well,  to  enter  which  the  water 
must  pass  through  a  porous 
partition  wall  made  of  bricks. 
These  walls  are  constructed  in 
various  ways :  one  form  is  rep- 
resented in  the  accompanying 
cut,  taken  from  "  Scribner's 
Monthly  Magazine "  for  Sep. 
tember,  1877. 

When  the  brick  partition  is 

new,  it  is  undoubtedly  of  good  service ;  but  it  soon  becomes 
clogged,  and  covered  on  the  outside  with  a  deposit  of  organic 
matter,  so  that  after  a  time  the  water  which  passes  through  the 
brick  wall  must  first  have  an  opportunity  to  leach  out  what  it 
can  from  this  mass  of  decaying  matter.*  As  a  rule,  the  interiors 
of  cisterns  are  not  very  accessible,  and  when  the  cistern  is  relied 
upon  as  the  sole  or  as  a  principal  supply  for  the  household,  it  is 
impossible  to  renew  frequently  the  filtering  wall,  or  even  to 
thoroughly  clean  the  outer  surface.  The  best  that  can  be  done 
under  ordinary  circumstances  is  to  clean  the  outer  surface  of  the 
wall  as  thoroughly  as  may  be  with  a  stiff  brush  every  few  months, 

*  Some  analyses  of  cistern  waters  thus  filtered  have  been  given  in  Table  V,  page  51. 


HOUSEHOLD  FILTRATION. 


177 


and  to  renew  the  wall  completely  whenever  the  probability  of  a 
rainy  season  allows.  If  the  body  of  the  cistern  be  divided  by  a 
partition  wall  into  two  compartments  which  may  be  made  to 
communicate  or  not  at  will,  the  two  may  be  cleaned  at  different 
times  and  thus  the  danger  of  a  water-famine  be  averted. 

Other  methods  for   accomplishing  filtration    in   the    cistern 

have  been  proposed.  Filters 
of  sand  and  charcoal,  or  of 
bone-coal,  are  sometimes  con- 
structed within  the  cisterns; 
but  they  are  not  easily  reach- 
ed for  cleaning,  and  as  a 
rule  they  are  allowed  to  go 
uncleaned.  Various  devices 


FIG.  37  (from  Fischer).  FIG.  38. 

have  been  suggested  for  attachment  to  the  suction  pipe  of  the 
pump,  two  of  which  are  shown  in  Figs.  37  and  38.  Fig.  37  is  a 
German  device  for  using  bone-coal  compressed  into  blocks  :  Fig. 
38  is  an  American  device  for  taking  the  water  as  free  from  the 
sediment  as  possible.  The  cylinder  contains  silicious  sand  for 
the  filtering  medium  and  is  buoyed  up  by  an  air-tight  chamber 
at  one  end.  The  pipe  has  a  swivel-joint  which  allows  the  filter 
12 


WATER   SUPPLY. 


to  accommodate  itself  to  the  level  of  the  water  in  the  cistern  oi 
reservoir.** 

Still  another  method  of  accomplishing  the  desired  object  con- 
sists in  placing  the  filtering  material  in  a  frame  capable  of  sliding 
in  a  groove  and  of  being  readily  lifted  from  its  place.  The  fil- 
tering material  may  consist  of  porous  tiles  or  of  blocks  of  animal 
charcoal ;  and,  if  duplicate  frames  are  provided,  the  grooves  may 
be  so  arranged  that  a  fresh  frame  can  be  lowered  into  place  be- 
fore the  old  one  is  taken  away.  Figure  39f  represents  a  cistern 
constructed  with  such  frames  containing  blocks  of  animal  char- 
coal, as  prepared  by  Atkins  &  Co.,  London.  These  blocks  can 
be  readily  cleaned  by  scraping  the  outer  surface  (at  some  expense, 
to  be  sure,  of  the  material  of  the  blocks),  and  they  can  be 
renewed  when  necessary.  They  are  made  of  various  densities; 
the  most  dense  permitting  the  passage  of  30  to  40  gallons  per 
square  foot  per  day,  while  the  most  porous  pass  some  250  to  300 


FIG.   39. 


gallons.     For  use  in  ordinary  cisterns   tolerably  porous   blocks 
would  probably  answer  well  enough,  and  for  such  use  as  this  the 

*  Scientific  American,  Jan.  10,  1880. 

f  This  cut  is  taken  from  Fanning's  Water-supply  Engineering. 


FILTRATION   FOR   MANUFACTURING  PURPOSES.  179 

charcoal  is  more  conveniently  employed  in  this  form  of  blocks 
than  as  fragments. 

The  arrangement  which  has  been  described  is  rather  expen- 
sive for  common  use ;  although,  if  the  necessary  provision  were 
made  in  the  original  plan  for  the  construction  of  the  cistern,  it 
would,  on  the  whole,  be  more  satisfactory  than  other  plans  which 
involve  less  outlay  at  the  start.  The  author  is  not  aware  that 
the  blocks  of  compressed  animal  charcoal  are  prepared  in  this 
country,  but  there  would  probably  be  no  difficulty  in  obtaining 
them  if  there  were  any  demand. 

There  is  one  point  worth  noting  in  connection  with  domestic 
filtration,  namely,  that  in  this  country  we  are  in  the  habit  of 
putting  ice  directly  into  the  pitchers  or  small  tanks  from  which 
drinking  water  is  served.  Natural  ice  is  not  always  clean,  and 
frequently,  after  the  ice  is  melted,  the  water,  even  if  clear  at 
the  start,  will  be  found  full  of  suspended  particles,  or  having  an 
abundant  sediment.  Filters  are  made  so  that  the  ice  cools  the 
water  before  the  filtration  takes  place  and  the  difficulty  can  also 
be  obviated  to  a  large  extent  by  inclosing  the  ice  in  a  clean  flan- 
nel or  cotton-flannel  bag. 

Filtration  for  Manufacturing  Purposes. 

For  the  majority  of  manufacturing  purposes  the  object  of 
filtration  is  accomplished  if  a  thorough  removal  of  suspended 
matter  is  effected.  Sand,  wood-charcoal,  bone-coal,  flannel  and 
various  other  substances  are  employed  as  filtering  media  ;  very 
good  results  are  obtained  by  the  use  of  sponge,  and  this  mate- 
rial is  employed  to  a  considerable  extent ;  in  some  cases,  the 
water  is  filtered  through  sand  filters,  similar  to  those  used  in 
connection  with  town  supplies  but  on  a  smaller  scale. 

Two  filters  have  recently  been  offered  in  the  market  to  effect 
rapid  filtration  for  manufacturing  purposes  and  also  for  town 
supply.  The  "  Multifold  Filter,"  manufactured  by  the  Newark 
Filter  Company,  may  be  of  various  sizes,  and  each  apparatus 
consists  of  a  number  of  shallow  cast-iron  pans  ranged  one  above 
the  other.  Each  pan  has  a  false  perforated  bottom,  on  which 
rests  a  layer  of  sand,  6  inches  or  less  in  thickness,  and  each 
works  as  an  independent  filter.  The  water  passes  in  the  di- 
rection of  the  arrows  shown  in  the  cut  under  a  greater  or  less 
pressure.  The  chief  peculiarity  of  the  filter  consists  in  the  ar- 


i8o 


WATER  SUPPLY. 


rangements  for   cleansing.     When   the    sand   becomes   clogged, 

water  is  introduced 
under  pressure 
through  the  hollow 
axis  of  the  cylinder, 
and  issues  in  fine 
jets  from  the  radial 
*~  arms,  stirring  up  the 
sand  and  washing 
away  the  lighter  sub- 
stances. The  arms 
can  be  revolved  from 
the  outside,  so  that 
the  sand  may  be  com- 
pletely washed. 

Another   filter 
(system  Piefke)    has 
FIG.  4°-  been  recently  adver- 

tised in  Germany,'*  where  the  filtering  medium  consists  of  cellu- 
lose (vegetable  fiber)  which  has  been  impregnated  with  some  anti- 
septic substance.  This  material  is  disposed  on  a  number  of  cir- 
cular sieves  arranged  one  above  another  in  an  apparatus  some- 
what similar  to  the  preceding,  and  a  thin  layer  suffices.  The 
filter  is  cleaned  by  revolving  the  vertical  axis  of  the  apparatus, 
which  is  a  rod  to  which  scrapers  are  attached ;  the  water  contin- 
ues to  flow  through  the  filters,  and  the  material  is  kept  in  sus- 
pension until  the  impurities  are  washed  away.  This  involves 
some  loss  of  the  prepared  cellulose,  but  it  is  claimed  that  the 
filtration  is  efficiently  and  cheaply  accomplished.  No  details  from 
disinterested  sources  are  at  hand  with  reference  to  the  practical 
value  of  either  of  these  devices,  which  seem  to  possess  certain 
merits. 

*  Journal  fiir  Gasbeleuchtung  und  Wasserversorgung,  March,  1883.     The  appa- 
ratus is  figured  and  described  in  the  Scientific  American,  April  28.  1883. 


CHAPTER  IX. 

ARTIFICIAL  IMPROVEMENT   OF  NATURAL  WATER  (Continued}. 
The  Softening  of  Hard   Water. 

As  has  already  been  explained  (page  33),  the  hardness  of 
water  is  generally  due  to  the  presence  of  compounds  of  lime  or 
magnesia.  While  a  moderately  hard  water  may  be  perfectly 
well  suited  for  drinking,  for  almost  all  the  other  purposes  of  a 
water  supply  a  soft  water  is  preferable,  other  things  being  equal. 
If  common  soap  be  added  to  hard  water  the  water  seems  to 
curdle,  but  no  permanent  froth  or  lather  is  formed  until,  by  the 
mutual  action  of  the  soap  and  the  compounds  of  lime  (and  mag- 
nesia) on  each  other,  the  latter  are  completely  converted  into  a 
lime  (or  magnesia)  soap,  an  insoluble  substance  which  forms  the 
curd  alluded  to.  After  this  point  is  reached,  any  additional  soap 
becomes  available  for  washing,  but  the  curdy  water  is  less  effi- 
cient as  a  detergent.  Hard  water  is,  as  a  rule,  much  less  desir- 
able for  culinary  purposes  than  soft  water.  Finally,  hard  water 
is  also  objectionable  on  account  of  the  "  scale"  which  forms  in 
steam  boilers  in  which  it  is  used :  in  manufacturing  towns  this 
becomes  a  matter  of  great  importance. 

Temporary  hardness. — The  temporary  hardness  is  due  to  the 
presence  of  carbonate  of  lime  or  magnesia :  these  compounds 
are  soluble  in  water  to  a  slight  extent  only,  but  are  brought  into 
solution  by  carbonic  acid,  as  has  been  explained  on  page  9:  it 
will  be  convenient  to  consider  them  as  existing  in  solution  as 
^carbonates.  The  temporary  hardness  of  a  water  may  be  re- 
moved in  various  ways :  in  the  first  place,  by  adding  soap,  as  is 
actually  done  when  an  attempt  is  made  to  wash  with  hard  water 
— a  method  uneconomical  on  the  small  scale,  and  impracticable 
on  the  large  scale  on  account  of  the  expense ;  in  the  second 
place,  by  adding  ordinary  washing-soda  (carbonate  of  soda) — a 
method  employed  very  generally  on  the  small  scale,  but  also 
impracticable  on  the  large  scale  on  account  of  expense.  The 


1 82  WATER   SUPPLY. 

chemical  explanation  of  the  second  method  is  this :  when  car- 
bonate of  soda  is  added  to  water  containing  bicarbonate  of  lime 
there  result  bicarbonate  of  soda  and  carbonate  of  lime  ;  the  former 
is  soluble  in  water  and  remains  in  solution,  the  latter  being  in- 
soluble separates  as  a  fine  powder.  A  simpler  method  still,  as 
the  explanation  of  the  term  "  temporary "  shows,  consists  in 
boiling  the  water  for  half  an  hour  or  more :  the  ^carbonate  of 
lime  (or  magnesia)  is  decomposed,  losing  half  its  carbonic  acid  ; 
this  carbonic  acid  escapes  as  gas,  and  the  simple  carbonate  of 
lime  separates  as  a  white  powder.  On  account  of  this  action, 
carbonate  of  lime  is  one  of  the  chief  constituents  of  boiler  scale, 
and  a  similar  deposit  forms  in  the  water-backs  of  kitchen  ranges, 
and,  in  fact,  in  any  vessel  in  which  the  water  is  boiled.  Some 
natural  waters  are  so  highly  charged  with  carbonate  of  lime  that 
slight  agitation  suffices  to  drive  off  the  "  extra  "  carbonic  acid 
and  to  allow  the  carbonate  to  separate ;  large  deposits  of  car- 
bonate of  lime  occur  in  nature  which  owe  their  origin  to  such  an 
action.  Fig.  41  (from  the  Scientific  American)  shows  a  portion 
of  the  feed-pipe  of  a  boiler  which  was  nearly  choked  up  by  the 
calcareous  matter. 

From  a  water  which  possesses  temporary  hardness,  the  car- 
bonate of  lime  may 
be  caused  to  deposit, 
and  the  water  thus 
become  softened,  not 
simply  by  expelling 
the  "  extra  "  carbonic 
acid  by  heat  or  other- 
wise, but  also  by  caus- 
ing this  carbonic  acid 
FIG.  41.  s 

to     unite     chemically 

with  some  substance  capable  of  thus  decomposing  the  bicarbon- 
ate. Caustic  soda  or  caustic  potash  will  produce  this  effect,  but 
the  cheapest  and  most  available  substance  is  ordinary  lime.  The 
lime  unites  with  the  extra  carbonic  acid  to  form  carbonate  of 
lime,  which  settles  out  as  a  fine  powder  along  with  the  carbonate 
originally  held  in  solution.  As  carbonate  of  lime  is  not  abso- 
lutely insoluble  in  water,  a  small  amount  remains  in  solution 
after  the  softening  has  been  completed,  not  enough,  however,  to 
be  seriously  objectionable. 


SOFTENING   OF   HARD   WATER.  183 

The  use  of  lime  was  invented  and  patented  about  the  year 
1844  by  Thomas  Clark,  professor  of  chemistry  in  the  University 
of  Aberdeen,  but  the  patent  expired  long  since.  The  process 
has  been  used  in  England  at  works  furnishing  as  much  as 
1,000,000  gallons  daily.  The  proper  amount  of  lime  is  added  in 
the  form  of  lime-water  or  milk  of  lime.  After  thorough  mixing 
the  water  is  allowed  to  subside  for  from  12  to  24  hours,  and 
drawn  off  from  the  sediment.  The  readiness  with  which  the 
finely  divided  carbonate  of  lime  settles  depends  somewhat  upon 
the  character  of  the  water  ;  and,  as  it  settles,  it  drags  down 
with  it  and  removes  from  the  water  a  not  inconsiderable  pro- 
portion of  the  organic  matter  present ;  if  the  water  is  colored 
by  peaty  matter,  a  very  appreciable  decolorization  is  effected. 
Experience,  however,  would  seem  to  show  that  the  process  gives 
the  best  results  with  water  which  is  naturally  clear,  such  as 
spring  water ;  and,  in  the  case  of  turbid  river  waters,  the  soft- 
ening process  should  be  followed  by  filtration. 

The  economy  of  the  process  and  the  advantage  of  softening 
a  hard  water  on  the  large  scale,  rather  than  by  the  use  of  soap  in 
the  household,  is  evident  when  we  consider  that,  to  soften  a 
quantity  of  water  requiring  one  hundred-weight  of  quicklime,  the 
expense  of  materials  would  be  (approximately) : 

I  cwt.  of  lime,  say $     o .  50 

5  cwt.  of  sal  soda  (at  1.2  cents  per  Ib.) 6.00 

20  cwt.  of  soap  (at  6|  cents  per  Ib.) 130.00 

Of  course,  on  a  large  scale  the  cost  of  labor,  and  especially  of 
handling  the  sludge,  may  make  the  actual  difference  less  than  the 
theoretical,  but,  in  any  event,  the  saving  in  soap  by  the  use  of 
the  softened  water  is  very  great. 

On  account  of  the  difficulty  with  which  the  carbonate  of  lime 
settles  in  waters  containing  much  organic  matter,  of  the  length 
of  time  required  and  of  the  necessarily  large  area  of  settling- 
basins,  the  process  is  seldom  carried  out  according  to  the  original 
plan.  There  are  various  modifications  of  the  process  which  aim 
to  accomplish  the  object  with  greater  economy  of  time  and  space, 
using,  however,  the  same  material.  These  modified  processes 
involve  some  form  of  filter  by  which  the  precipitated  carbonate 
of  lime  may  be  removed  at  once  without  waiting  for  the  sub- 


1 84 


WATER   SUPPLY. 


sidence  to  take  place.     It  will  suffice  to  describe  one  of  these 
processes. 

In  England  a  number  of  manufacturing  establishments  and 
several  towns  have  introduced  Clark's  process  as  modified  by 
J.  H.  Porter,  C.  E.*  The  lime  is  employed  in  the  form  of  a 
saturated  solution,  and  the  mixing  with  the  bulk  of  the  water  to 
be  softened  takes  place  in  a  separate  tank  from  that  in  which  the 
solution  is  prepared.  When  thorough  mixture  has  been  effected, 
the  liquid  is  at  once  filtered  through  cloth.  The  arrangement 
and  construction  of  the  tanks  varies  with  the  quantity  of  water 


PORTER-CLARK     PROCESS 
FOR    SOFTENING     &    PURIFYING     WATER 


FIG.  42. 

to  be  softened.     Fig.  42  represents  an  apparatus  for  treating  300 
gallons  of  water  per  hour.     The  preparation  of  the  lime-water 

*  The  Porter-Clark  Process  for  the  Softening,  Purification  and  Filtration  of  Hard 
Waters,  by  John  Henderson  Porter,  London. 


SOFTENING   OF  HARD   WATER. 


I85 


takes  place  in  the  left-hand  cylinder,  which  is  furnished  with  a 
mechanical  stirrer;  the  mixing  takes  place  in  the  right-hand 
cylinder  ;  the  other  details  of  the  apparatus  are  evident  from 
the  figure.  The  filtration  of  the  mixture  may  be  accomplished 
by  any  one  of  a  variety  of  filter  presses ;  that  employed  by  Mr. 
Porter  is  shown  in  Fig.  42  and  more  plainly  in  Figures  43,  44 
and  45.  Fig.  43  shows  a  portion  of  the  filters  used  by  the  Lon- 


43. 


don  and  North-western  Railway  Company  at  Liverpool,  where 
over  200,000  U.  S.  gallons  of  water  are  softened  daily.  Each 
filter  is  made  up  of  a  series  of  cast-iron  plates  and  cast-iron  open 
frames  of  the  form  shown  in  Figs.  44  and  45.  "  Over  these  filtering 


FIG.  44. 


FIG.  45. 


chambers,  of  about  I  inch  in  thickness,  is  dropped  (as  a  towel  plac- 
ed upon  a  towel-horse)  a  cloth  of  superior  quality  of  cotton  twill, 
having  worked  in  it  holes  to  correspond  with  the  holes  through  the 
upper  corners  of  both  water-space  frame  and  filtering  chambers. 
When  these  alternate  water  spaces  and  filtering  chambers  with 


186  WATER   SUPPLY. 

the  cloths  are  tightly  pressed  together  by  a  powerful  end  screw, 
it  will  be  seen  that  the  holes  become,  collectively,  tubular  chan- 
nels of  the  length  of  the  '  battery,'  the  channel  of  the  one  side 
admitting  its  chalky  water  to  the  circular  water-spaces,  whence, 
being  inclosed  and  under  pressure,  it  can  only  escape  through 
the  adjoining  cloths  into  the  concentric  and  radiating  grooves 
which  conduct  it  by  a  small  outlet  to  the  channel  on  the  other 
side." 

In  the  figure  (Fig.  43)  the  left-hand  filter  is  represented  as  un- 
screwed and  with  two  of  the  cloths  raised  for  purposes  of  clean- 
ing. The  cloths  are  readily  removed  and  replaced  by  a  fresh  set  as 
often  as  may  be  necessary — how  often  depends  upon  the  amount 
and  the  character  of  the  impurity,  other  than  the  chemically 
formed  chalk,  present  in  the  water.  At  Liverpool  and  other 
places  where  the  waters  are  from  deep  wells  in  the  chalk  or  red 
sandstone,  the  filters  run  for  15  hours  without  changing  the 
cloths  and  the  labor  of  one  man  is  found  sufficient  to  cleanse 
cloths,  and  filters  and  to  attend  to  other  details  of  the  process  in 
softening  150,000  to  180,000  (imperial)  gallons  for  the  day's  work. 
In  other  places,  where  the  water  contains  a  larger  proportion  of 
magnesia  or  surface  impurities,  the  filters  may  not  run  for  more 
than  6  or  7  hours  without  cleansing. 

From  the  application  of  Clark's  process,  in  whatever  form, 
there  results  a  large  quantity  of  chalk  or  "  whiting,"  more  or  less 
pure  according  to  the  amount  of  impurity  in  the  water  softened. 
If  the  water  contains  organic  matters,  a  portion  is  precipitated 
along  with  the  chalk,  together  with  any  sediment  which  the 
water  may  contain.  In  some  localities  there  is  a  market  for  the 
whiting  which  tends  to  offset  the  expenses  of  the  process.  A 
portion  might  be  burned  into  lime  and  used  over  again  in  soft- 
ening afresh  portion  of  water,  but  being  in  a  fine  powder  it  could 
not  be  burned  in  ordinary  kilns. 

Permanent  hardness. —  The  permanent  hardness  is  usually 
caused  by  the  presence  of  the  sulphates  (or  other  soluble  salts) 
of  lime  and  magnesia,  gypsum  (sulphate  of  lime)  being  the  most 
common ;  the  action  on  soap  is  the  same  as  that  of  the  bicar- 
bonates,  which  has  been  discussed  under  temporary  hardness. 
Water  containing  sulphate  of  lime  may  be  softened  by  adding 
carbonate  of  soda,  and  this  is  the  method  commonly  employed 
in  the  laundry.  The  chemistry  of  the  process  is  this :  when  car- 


TREATMENT   BY   CHEMICAL  PROCESSES.  l8/ 

bonate  of  soda  in  solution  is  mixed  with  sulphate  of  lime  in  solu- 
tion, there  are  formed  carbonate  of  lime  (which  settles  out  in  the 
solid  form)  and  sulphate  of  soda  (which  remains  dissolved) ;  a 
similar  action  takes  place  with  other  soluble  compounds  of  lime 
and  magnesia.  The  expense  of  this  treatment  makes  it  imprac- 
ticable to  soften,  in  this  way,  the  entire  water  supply  of  a  town, 
a  large  portion  of  which  is  used  for  purposes  where  the  hardness 
of  the  water  is  a  matter  of  indifference.  We  have  seen  (page  5) 
that  sulphate  of  lime  becomes  insoluble  in  water  at  high  tem- 
peratures and  contributes  to  the  formation  of  scale  in  steam- 
boilers  ;  hence,  for  technical  purposes,  it  is  desirable  to  remove 
the  sulphate,  and  the  process  just  indicated,  or  some  other  method, 
may  be  employed  to  advantage. 

Treatment  by  other  Chemical  Processes. 

On  the  large  scale,  attempts  are  seldom  made  to  improve  a 
natural  water  except  by  processes  which  have  already  been  de- 
scribed ;  there  are,  however,  a  number  of  substances  which  may 
be  used  to  advantage  in  purifying  the  small  quantity  necessary 
for  drinking  in  localities  where  no  really  drinkable  water  exists. 
One  of  the  longest  used  and  best  known  substances  is  common 
alum,  which  is  often  added  to  a  turbid  water.  Where  the  water 
contains  carbonate  of  lime  in  solution,  a  chemical  action  takes 
place  between  it  and  the  alum,  resulting  in  the  formation  of  sul- 
phate of  lime,  which  remains  dissolved,  of  carbonic  acid,  which  es- 
capes as  gas,  and  of  hydrate  of  alumina,  which  separates  out  as  a 
solid.  As  the  hydrate  of  alumina  forms  and  settles  down,  it  entan- 
gles and  drags  down  with  it  the  finely  divided  suspended  matter 
to  which  the  turbidity  is  due  :  in  fact,  it  enters  into  some  sort  of 
chemical  combination  with  some  of  the  dissolved  organic  matter 
which  is  thus  removed.  When  the  water  does  not  contain 
enough  carbonate  of  lime  or  other  substance  capable  of  decom- 
posing the  alum,  the  addition  of  the  alum  may  be  followed 
by  the  addition  of  a  proper  amount  of  carbonate  of  soda.  Per- 
chloride  (or  other  soluble  persalt)  of  iron  acts  very  similarly  to 
alum.  Instead  of  hydrate  of  alumina,  it  is  the  hydrate  of  iron 
(ferric  hydrate)  which  is  formed,  and  this  also,  in  settling,  carries 
with  it  some  organic  matter.  It  was  at  one  time  proposed  to 
treat  the  water  of  the  Seine  at  Paris  with  alum,  and  the  use  of 


1 88  WATER   SUPPLY. 

perchloride  of  iron  and  carbonate  of  soda  were  talked  of  for  ren- 
dering potable  the  water  of  the  Maas  in  Holland. 

Another  substance  which  has  more  recently  come  into  notice 
is  permanganate  of  potash.  The  action  is  the  same  as  that  de- 
scribed when  discussing  the  use  of  this  substance  as  a  means  of 
determining  analytically  the  amount  of  organic  matter  present 
in  a  water.  (See  page  37.)  In  attempting  to  purify  an  impure 
water  by  this  means,  the  highly  colored  solution  of  the  perman- 
ganate must  be  added  in  quantity  sufficient  to  impart  a  pink 
color,  which  remains  permanent  for  from  five  to  ten  minutes. 
The  permanganate,  in  destroying  the  organic  matter,  is  itself 
decomposed,  and  oxide  (or  hydrate)  of  manganese  separates  as  a 
finely  divided  solid.  This  may  be  removed  by  filtration,  or  it 
may  simply  be  allowed  to  settle  to  the  bottom  of  the  tanks  in 
which  the  water  is  treated.  Other  permanganates  may  be  used 
as  well  as  that  of  potash.  For  the  treatment  of  the  water  which 
the  British  army  was  likely  to  meet  with  upon  the  Gold  Coast, 
Professor  Crookes,*  in  1873,  recommended  a  mixture  of 

I  part  of  permanganate  of  lime, 
10  parts  of  sulphate  of  alumina, 
30  parts  of  fine  clay. 

He  stated  that  this  mixture,  when  added  to  London  sewage  in 
the  proportion  of  20  to  10,000,  afforded  a  very  satisfactory  puri- 
fication. 

The  most  simple  manner  of  treating  a  water  known  or  sus- 
pected to  be  impure  is  to  boil  it,  although  it  is  by  no  means  cer- 
tain that  immunity  from  harm  is  thus,  in  all  cases,  assured. 
There  is,  however,  evidence  to  show  the  value  of  the  treatment ; 
if,  after  the  boiling,  the  water  is  iced,  it  becomes,  of  course,  more 
palatable.  It  is  stated  that  the  Chinese  and  Japanese  drink  no 
water  that  has  not  been  boiled  ;  and  when  we  consider  the  un- 
sanitary conditions  which  exist  in  those  countries  and  the  char- 
acter of  the  water  used,  it  seems  as  if  boiling  the  water  must 
prevent  ills  that  would  otherwise  befall  the  people. 

In  some  instances  lime  has  been  added  to  water  which  is  used 
for  domestic  supply — the  lime  being  added  for  purposes  other 
than  the  softening  of  a  water  containing  the  bicarbonates.  Thus, 
in  Australia,  at  Sandhurst,  Victoria,  the  impounded  surface  water 

*  Chemical  News,  xxviii  (1873),  p.  244. 


DISTILLATION. 


189 


which  is  used  contains  at  times  as  much  as  30  or  40  grains  of 
yellowish-brown  clayey  matter -in  the  (imperial)  gallon,  i.e.,  say 
about  50  parts  in  100,000.  Here  it  was  found  that  sand  filters 
did  not  thoroughly  intercept  the  clay  in  suspension,  and  that 
the  water,  after  filtration,  still  remained  cloudy  and  opalescent. 
Lime  was  added  at  the  rate  of  7  grains  to  the  (imperial)  gallon, 
and  after  standing  10  hours  the  water  became  clear:  five-sevenths 
of  the  added  lime  went  down  with  the  precipitate,  the  other  two- 
sevenths  remained  in  solution  in  the  water,  and  of  course  gave 
it  a  slight  hardness.  At  several  other  works  lime  is  used  in  the 
same  proportion,  and  this  treatment  is,  in  some  cases,  followed 
by  filtration,  in  others  not.  The  capacity  of  one  of  the  works 
where  this  treatment  is  employed  is  as  great  as  1,000,000  imperial 
gallons  per  day.*'"" 

Distillation. 

The  ordinary  process  of  distillation  is  sufficiently  familiar. 
When  water  is  boiled,  the  gaseous  substances  which  it  holds  in 
solution  are  expelled  almost  completely,  either  while  the  water 
is  heating  up  to  the  boiling  point,  or  with  the  first  portion  of 
the  steam :  the  dissolved  solids,  on  the  other  hand,  remain  be- 
hind while  the  water  evaporates.  If  the  water  be  boiled  in  an 


FIG.  46. 

ordinary  still — such,  for  instance,  as  is  shown  in  Fig.  46 — and 
the  steam  be  subsequently  condensed,  the  water  which  issues 
from  the  condenser  will  be  tolerably  pure,  especially  if  the  first 

*  Brady  :  Froc.  Inst.  Civ.  Eng.  Gr.  Br.  Ivi,  p.  134  and  foil. 


IQO  WATER   SUPPLY. 

portions  be  rejected  and  the  evaporation  be  not  carried  too  far. 
Distillation  is,  of  course,  a  somewhat  expensive  process,  for  be- 
sides the  cost  of  the  necessary  apparatus,  each  pound  of  water 
evaporated  requires  the  consumption  of  from  one-twelfth  to  one- 
seventh  of  a  pound  of  coal,  according  to  the  quality  of  the  coal 
used  and  the  efficiency  of  the  boiler  employed.  On  this  account, 
distilled  water  for  drinking,  cooking,  and  other  domestic  uses  is 
seldom  prepared  on  any  considerable  scale  except  on  shipboard. 
Here,  the  steam  is  usually  taken  from  one  of  the  boilers  used  to 
generate  steam  for  the  motive  power  of  the  ship,  and  the  differ- 
ent systems  consist  in  differences  in  the  condensers  (aerators  and 
purifiers),  although  the  term  "  distiller  "  is  often  applied  to  this 
part  of  the  apparatus.  The  condensers  are  of  various  forms — 
the  ordinary  worm,  the  flat  worm  or  zigzag,  and  the  tube  con- 
denser, consisting  of  a  cylinder  with  tubes  inside  running  verti- 
cally, the  steam  passing  through  the  tubes  and  the  water  being 
on  the  outside,  or  vice  versa. 

Ordinary  distilled  water  has  a  flat  and  nauseous  taste,  owing 
partly  to  the  fact  that  the  dissolved  gases,  notably  oxygen  and 
carbonic  acid,  have  been  expelled,  and  partly  to  the  presence  of 
certain  volatile  organic  compounds  which  have  been  formed 
during  the  distillation.  This  is  often  remedied  by  allowing  the 
water  to  remain  for  from  10  to  15  days  in  partly  filled  tanks 
where  it  will  be  exposed  to  the  air  and  more  or  less  agitated  by 
the  motion  of  the  ship.  A  number  of  devices  have  been  con- 
trived and  patented  which  aim  to  accomplish  this  aeration  and 
oxidation  at  once,  and  thus  to  produce  a  distilled  water  fit  for 
immediate  use. 

In  the  United  States  navy,  a  condenser  invented  by  Passed 
Assistant  Engineer  G.  W.  Baird  is  largely  used.  The  essential 
feature  of  this  system  is  the  introduction  of  air  into  the  apparatus 
in  such  a  way  that  it  mixes  with  the  steam,  and  the  water  which 
forms  is  condensed  in  the  presence  of  an  abundance  of  oxygen, 
and  thus  becomes  fully  aerated.  It  is  further  claimed  that  the 
air  so  introduced  oxidizes  the  organic  matter  carried  forward  by 
the  steam.  This  it  no  doubt  does,  if  not  at  once,  at  least  when 
the  water,  thus  aerated,  is  subsequently  passed  through  a  filter 
of  purified  animal  charcoal.  Fig.  47  represents  the  condenser  in 
section.  The  steam  enters  at  a  and,  on  the  principle  of  an 
injector,  draws  air  in  through  b;  the  mixture  of  air  and  steam 


DISTILLATION. 


enters  the  system  of  cooling  pipes  B,  where  the  steam  is  con- 
densed.    The  pipes  are  usually,  of  cylindrical  section  and  are 


FIG.  47.  — BAIRD'S  CONDENSER. 

made  of  tin  or  tinned  copper ;  they  are  coiled  into  helices,  the 
ends  terminating  in  the  common  T-heads,  C,  C,  at  the  upper  and 
lower  ends  respectively.  The  refrigerating  water  enters  at  d  and 
is  discharged  at  e,  and  the  condensed  water  flows  out  at  f  and 
thence  passes  to  the  filter.  In  the  U.  S.  navy  the  water  is  not 
salified  and  is  regarded  as  perfectly  wholesome.  It  is  stated  * 
that  in  the  Russian  navy  there  is  added  to  each  l,ooo  liters  of 
distilled  water  a  mixture  consisting  of  4.8  grams  salt,  3.4  grams 

*  Fonssagrives  :  Hygiene  et  assainissement  des  villes  ;  Paris,  1874,  p.  316. 


192 


WATER   SUPPLY. 


sulphate  of  soda,  48  grams  bicarbonate  (sic)  ( f  lime,   14  grams 
bicarbonate  of  soda,  and  6  grams  carbonate  of  magnesia. 

The  British  navy  uses  Normandy's  system,  and  essentially  the 
same  apparatus  is  used  in  the  German  navy,  as  shown  in  Figs. 
48  and  49.*  The  apparatus  consists  essentially  of  two  cylinders, 
the  two  sectional  views  of  B  being  taken  at  right  angles  to  each 
other.  Steam  is  generated  in  a  separate  boiler  and  enters  the 
cylinder  A  through  the  pipe  d,  and  passes  into  the  sheaf  of  tubes 

b  which  are  surrounded 
by  water  which  is  to  be 
distilled.  The  watei 


FIG.  48.  FIG.  49. 

formed  by  condensation  collects  in  the  reservoir  e  at  the  base 

of  the  sheaf  of  pipes,  and  from  here  it  flows  into  the  vessel  g, 

shown  only  in  Fig.  48 ;  if  the  water  is  required  warm,  it  may  be 

*  Fischer  :  Chemische  Technologic  des  Wassers..  p.  205  and  foil. 


DISTILLATION.  IQ3 

drawn  from  g  directly,  otherwise  it  flows  through  a  connecting 
pipe  into  the  lower  sheaf  of  tubes  in  the  cylinder  B.  The  level 
of  the  water  in  A — which  flows  in  from  B — is  so  regulated  that 
the  steam  which  is  formed  may  free  itself  from  any  salt  water 
which  it  carries  mechanically,  by  passing  first  through  the  per- 
forated copper  plate  a,  and  then  by  striking  against  c,  before  it 
passes  through  the  pipe  m  into  the  sheaf  of  tubes  n  in  the  upper 
part  of  the  cylinder  B.  The  water  which  is  here  condensed  flows, 
for  further  cooling,  into  the  lower  sheaf  of  tubes  in  B,  into  which 
the  water  condensed  in  b  also  flows,  and  which  is  the  set  of  tubes 
with  which  the  cooling  water  entering  at  i  comes  in  contact. 
The  water,  thus  fully  cooled,  is  either  discharged  directly  through 
the  tube  r,  or  is  conducted  through  s  to  a  simple  filter  filled  with 
animal  charcoal.  The  water  used  in  cooling  enters  through  the 
tube  i  and  flows  off  through  k,  except  so  much  as  is  necessary  to 
keep  the  level  of  the  water  in  A  at  the  proper  height.  The  air 
which  escapes  from  the  water  as  it  becomes  warm  is  conducted 
through  the  tube  t  into  the  steam  space  of  the  distilling  ap- 
paratus, in  order  that  the  water,  as  it  condenses,  may  dissolve  it 
again  and  thus  become  more  palatable.  By  means  of  the  con- 
nection jj>  the  return  steam  from  the  steam  pump  may  be  allowed 
to  enter  A,  to  be  utilized  in  the  production  of  distilled  water. 
Finally,  when  the  water  in  the  distilling  apparatus,  A,  becomes 
too  concentrated,  it  may  be  withdrawn  by  means  of  a  cock  not 
shown  in  the  figures. 

While  distilled  water  is  seldom  prepared  on  a  large  scale  ex- 
cept on  shipboard,  there  are  some  localities  where  drinking  water 
cannot  otherwise  be  procured,  and  distillation  must  be  resorted 
to.  For  example,  the  island  of  Walcheren,  in  Holland,  is  de- 
pendent for  its  supply  of  fresh  water  for  drinking  on  the  rainfall, 
all  other  water  being  brackish.  For  the  supply  of  ships  leaving 
the  harbor  of  Flushing  (Vlissingen),  it  has  been  necessary  to  have 
recourse  to  the  condensation  of  steam,  as  being  the  only  avail- 
able source  of  fresh  water  independent  of  rain  ;  Normandy's  ap- 
paratus is  employed.  It  is  stated  *  that  the  plant  cost  20,000 
Dutch  florins  (about  $12,000),  and  that  18  kilograms  of  distilled 
water  are  produced  for  each  kilogram  of  coal  burned,  the  water 
being  distilled  at  the  rate  of  one  cubic  meter  per  hour  and  being 
of  satisfactory  quality. 

*Proc.  Inst.  Civ.  Eng.  Gr.  Br.,  Ixii,  p.  408. 
13 


CHAPTER  X. 

SOME  GENERAL  CONSIDERATIONS. 
Quantity  and  Waste. 

WHATEVER  source  may  be  chosen  for  the  supply  of  a  city  or 
town,  it  is  essential  that  the  quantity  of  water  should  be  suffi- 
cient for  the  needs  of  the  population  for  a  number  of  years. 
The  experience  of  many  places  has  been  similar  to  that  of  New 
York  City.  Within  eight  years  after  the  completion  of  the  Cro- 
ton  aqueduct,  the  New  York  Water  Department  wrote  :  "  This 
Board  warns  the  City  Council,  and  through  it  every  citizen,  that 
every  drop  of  water  which  the  works  in  their  present  state  can 
supply  is  now  being  delivered  in  the  city."  What  is,  however,  a 
sufficient  quantity  ?  The  following  table  gives  the  amount  of 
water  per  head  of  population  consumed  in  certain  European 
cities : 

TABLE  XXVI. — CONSUMPTION  OF  WATER  IN  EUROPEAN  CITIES. 


CITIES  (1880).  * 

DAILY  AVERAC 

PER  HEAI 

U.  S.  Gallons. 

,E  SUPPLY 

),  IN 

Litres. 

CITIES,  t 

DAILY  AVERAC 

PER  HEAI 

U.  S.  Gallons. 

,E  SUPPLY 

),  IN 

Litres. 

60 

50.2 
48 
45-6 
39-2 
30 
30 
27.9 
27 
24 

21.6 

227 
IQO 
I8l 
172 
148 
"3 
H3 
107 
104 

91 

82 

Karlsruhe     .        .... 

154 
76 

63 
60 

59 
53 
43 
4i 
39 
33 
3i 
31 
23 

581 
289 
237 
228 
223 
200 
I63 

154 

I4S 
124 

116 

H5 
86 

Paris 

Bonn 

Edinburgh  

Hamburg 

Dublin 

Hull                   .  .      . 

Frankfurt  a.  M  
Coin      ... 

Birmingham  ..    ..... 

Blackburn 

Leeds                .  .      . 

Braunschweig 

Liverpool  

Bamberg    

Manchester  

Kassel  

Sheffield    

Hannover                . 

Altona     

Leipzig 

The  estimates  of  European   experts  as  to  the   amount   of 
water  necessary  for  an  adequate  supply  must  be  received  with 

*  Brackett :  Journ.  Assoc.  Eng.  Soc.,  I  (1882),  p.  261. 

\  Grahn  :  Journ.  f .  Gas>beleuchtung  u.  Wasserversorgung,  xx  (1877). 


QUANTITY  AND   WASTE. 


195 


some  caution  as  applied  to  American  circumstances,  owing  to 
difference  in  a  variety  of  conditions.  The  following  table  shows 
the  actual  consumption  in  a  number  of  American  cities:  * 

TABLE  XXVI. — CONSUMPTION  OF  WATER  IN  AMERICAN  CITIES. 


AMERICAN-  CITIES. 

YEAR. 

POPULATION. 

Average  Daily 
Consumption. 
Gallons. 

Gallons 
per  head 
per  day. 

Litres 
per  head 
per  day. 

Fall  River 

1881 

4Q-43O 

I  4.48,247 

<?Q    I 

114. 

Providence                           .  .  . 

IO2  5OO 

3  7l6  Q37 

36  3 

137 

Lowell        

1880 

^0,485 

2,252,IQ7 

37    Q 

I43 

1881 

52,880 

2,472,108 

•*!?" 

46  7 

177 

1880 

566,689 

30,744,590 

54.2 

205 

Philadelphia 

a 

847  542 

c7  707  082 

68  i 

257 

St    Louis                        

1870 

•346  ooo 

24,058,000 

72  I 

273 

Cincinnati  

l83o 

2^6,708 

IQ,476,73Q 

75.0 

287 

I  2o6   5OO 

95  ooo  ooo 

78  7 

2Q7 

Boston             .               .  . 

1881 

416  ooo 

38  214  QOO 

02 

348 

Chicago          .        

1880 

CQ3   -3Q4 

57,384  376 

114 

471 

Detroit  

1881 

llS  OOO 

17,026,377 

I5I.Q 

C74 

From  this  table  it  is  evident  that  there  is  a  great  difference 
in  the  amount  of  water  consumed  in  different  places,  and  if  from 
30  to  50  gallons  suffice  in  certain  cities,  the  use  of  90  or  100 
gallons  in  others  presupposes  a  considerable  waste :  in  fact,  it  is 
generally  agreed  by  those  in  charge  of  water  supplies  that  from 
a  quarter  to  one-half  of  the  water  furnished  is  actually  wasted. 
Mr.  Thos.  J.  Whitman,  of  the  St.  Louis  water  works,  said,  a  few 
years  ago,  that  it  cost  the  city  fully  $300,000  annually  in  fuel 
alone  to  simply  supply  the  waste,  and  similar  statements  come 
from  all  large  cities.  For  domestic  and  household  uses  20  gal- 
lons per  person  per  day  is  a  sufficient  allowance :  taking  into 
account  the  water  used  for  manufacturing  and  mechanical  pur- 
poses, that  necessary  for  street  sprinkling,  extinguishing  fires, 
for  use  in  stables,  etc.,  60  gallons  per  day  for  each  inhabitant  is 
a  liberal  quantity  in  the  case  of  large  cities  and  manufacturing 
towns.  In  the  case  of  the  smaller,  non-manufacturing  towns  35 
or  40  gallons  should  suffice.  Mr.  Dexter  Brackett,  in  a  valuable 
paper  on  the  waste  of  water,  from  which  Table  XXVI  and  a 
part  of  Table  XXV  have  been  taken,  considers  50  gallons  per 
head  as  sufficient  to  provide  for  all  the  demands  of  the  largest 
cities  of  the  country. 

The  great  waste  which  takes  place  being  acknowledged,  the 

*  Brackett:  Journ.  Assoc.  Eng.  Soc.,  I,  p.  261. 


196  WATER   SUPPLY. 

question  arises  how  to  prevent,  or  at  least  diminish  it.  There 
are  two  general  methods  which  suggest  themselves.  The  first  is 
a  rigid  system  of  inspection  in  order  to  detect  all  leakage  from 
the  pipes  and  from  imperfect  fixtures,  as  well  as  all  unlawful  use 
of  the  water ;  the  second  is  the  general  and  compulsory  intro- 
duction of  meters.  With  reference  to  the  first  method,  although 
the  authorities  in  charge  of  the  distribution  of  water  reserve  the 
right  to  inspect  the  fixtures  at  any  time,  yet  such  inspection  is 
annoying  and  repugnant  to  the  average  householder,  and  the 
system  admits  of  abuse.  A  modification  of  this  system,  which 
obviates  the  necessity  of  entering  the  building  except  in  cases 
where  abnormal  use  of  water  is  already  known  to  exist,  is  that 
devised  by  Mr.  G.  F.  Deacon,  Borough  Engineer,  Liverpool, 
England.*  The  following  description  of  the  system  is  taken 
from  a  report  on  waste  of  water  made  to  the  City  Council  of  Bos- 
ton, Mass.f 

"  In  the  Deacon  system  the  waste-water  meter  is  used  to  locate 
sources  of  waste.  This  meter  does  not,  like  the  ordinary  meter, 
record  the  number  of  gallons  consumed,  but  it  indicates  the  rate 
of  flow  at  any  given  time,  and  whether  the  discharge  is  due  to 
steadily  flowing  waste,  or  to  intermittent  and  ordinary  use.  It 
therefore  enables  the  observer  to  determine,  by  observations 
taken  at  those  hours  when  no  water,  or  a  very  small  quantity,  is 
used  for  legitimate  purposes,  whether  waste  is  going  on. 

"  The  meter  (Fig.  50)  ^  consists  of  a  hollow  cone,  having  its 
small  end  upwards,  and  containing  a  composition  disk,  of  the  same 
diameter  as  the  small  end  of  the  cone.  A  vertical  spindle,  attached 
to  the  upper  surface  of  this  disk,  is  suspended  by  a  fine  German- 
silver  wire,  which  passes,  practically  water-tight,  through  a  small 
hole  in  the  top  of  the  chamber,  over  a  pulley,  and  supports  a 
weight.  This  weight  is  so  adjusted  as  to  retain  the  disk  at  the 
top  of  the  cone  when  the  water  is  at  rest.  When  any  water  is 
drawn  through  the  meter,  the  disk  is  pressed  downward  towards 
the  bottom  of  the  cone,  its  position  depending  upon  the  amount 

*  A  valuable  report  of  Mr.  Deacon  is  reprinted  in  the  Report  of  the  Cochituate 
Water  Board  of  the  City  of  Boston,  for  the  year  ending  April  30,  1874.  City  Docu- 
ment No.  55,  pages  84-112. 

f  Report  on  Waste  of  Water  (May  25,  1882).   Boston  City  Document  No.  78,1882. 

J  Figure  50  is  reduced  from  a  plate  in  a  paper  on  The  Constant  Supply  and 
Waste  of  Water,  by  Geo.  F.  Deacon,  in  the  Journal  of  the  Society  of  Arts,  May,  1882. 


FOUR  INCH  DEACON  WASTE  WATER  METER. 


A  Inlet. 

B  Outlet. 

C  Gauge  Cone. 

D  Disk. 

E  Stem  of  Disk. 

F  Guide  for  Stem. 

G  Wire  connecting 
Disk  with  Pen- 
cil Carriage. 


Bushes. 

I    Pencil  Carriage. 
L  Counter  balance. 
M  Clock. 


/z  INCHES 


FIG.  50. 


198 


WATER  SUPPLY. 


of  water   passing   through   the   meter. 


A.M.,  only  occasionally  broken  by  vertical 
drawing  water  during  the  night. 


By  means  of  a  pen- 
cil attached  to  the 
wire  the  motions  of 
the  disk  are  record- 
ed on  a  drum,  which 
revolves  by  clock- 
work, once  in  24 
hours. 

"  A  fac-simile, 
about  one-fifth 
full  size,  of  a  dia- 
gram drawn  auto- 
matically  by  a 
waste-water  meter, 
is  shown  in  Fig.  51. 
It  is  obvious  that 
when  water  is  being 
drawn  off  for  use 
the  rate  of  flow 
from  minute  to 
minute  must  be  va- 
riable ;  and  this  is 
accordingly  shown 
by  the  irregular 
vertical  lines  from 
noon  to  midnight, 
and  from  4  A.  M.  to 
noon.  When  con- 
tin  u  o  u  s — that  is, 
preventable,  waste 
alone  is  takingplace 
— the  flow  must  evi- 
dently be  uniform ; 
and  this  condition 
is  indicated  by  the 
comparatively  uni- 
form and  horizontal 
line  from  I  to  4 
lines,  caused  by  persons 


QUANTITY  ANP   WASTE.  199 

"The  meter  is  placed  in  a  box  under  the  sidewalk  or  roadway, 
and  so  located  as  to  control  the  flow  of  water  supplied  to  a  cer- 
tain district,  the  limits  of  which  have  been  previously  determined. 
All  the  water  used  in  this  district  is  drawn  through  the  meter, 
and  the  quantity  and  rate  recorded.  After  a  few  diagrams  have 
been  taken,  to  show  the  ordinary  rate  of  consumption,  inspection 
is  commenced.  Every  service  pipe  is  provided  with  a  stopcock, 
which  is  accessible  from  the  sidewalk  by  means  of  an  iron  wrench 
about  seven  feet  long.  When  this  wrench  is  applied  to  the  stop- 
cock the  sound  caused  by  water  passing  through  the  service  pipe 
can  be  easily  distinguished.  When  no  noise  is  heard,  with  the 
stopcock  fully  open,  it  is  partly  closed,  and  the  increased  velocity 
always  causes  a  distinct  sound,  although  the  quantity  of  water 
passing  the  stopcock  may  be  very  small.  A  night  inspector  be_ 
gins  his  work  about  midnight,  and  tests,  by  means  of  hfs  shutting- 
off  wrench,  each  service  pipe.  If  he  discovers  any  flow  through 
the  service  pipe,  the  stopcock  is  closed,  and  a  note  made  of  the 
time  and  the  number  of  the  house.  He  continues  this  operation 
through  the  district  until  about  4  A.M.,  when  he  retraces  his 
steps,  and  opens  all  the  stopcocks  he  had  found  wasting.  Dur- 
ing this  time  the  meter  is  recording  the  consumption,  and  the 
diagrams  show  the  amount  of  water  wasted  by  each  of  the  ser- 
vice pipes  that  were  closed,  the  time  the  inspector  began  and 
finished  his  work,  and  the  time  each  stopcock  was  closed.  The 
day  inspector  receives  the  night  inspector's  report,  visits  the 
premises  where  waste  was  noted,  and  ascertains  the  cause.  In 
cases  of  waste  from  defective  fixtures  the  owners  are  notified  to 
repair  the  same,  and  the  visits  are  continued  until  the  notices 
have  been  complied  with. 

"  The  economy  of  this  system,  as  compared  with  house-to- 
house  inspection,  is  apparent.  The  attention  of  the  inspector  is 
at  once  directed  to  the  place  where  the  waste  is  going  on,  and 
the  time  lost  in  indiscriminate  inspection  is  saved." 

The  Deacon  system  has  given  very  satisfactory  results  where- 
ever  tried.  The  chairman  of  the  Liverpool  Water  Committee, 
in  his  address  in  1879,  sa^  : 

"We  have  given  the  city  a  constant  service*  of  water,  with  a 

*  Before  the  introduction  of  the  Deacon  system  of  inspection,  the  supply  of  Liv- 
erpool was  an  intermittent  one,  the  water  being  on  only  g$  hours  out  of  the  24. 


200 


WATER  SUPPLY. 


decline  in  the  death-rate,  and  it  now  remains  for  me  to  show 
what  other  effects  have  arisen  from  the  change  of  system.  In 
the  year  1871  we  delivered  an  average  of  122,000,000  gallons 
weekly  ;  in  1880  our  deliveries  will  be  about  115,000,000  gallons; 
and  this,  notwithstanding  an  increased  sale  for  trade  purposes 
of  12,250,000  gallons  weekly,  and  an  increased  population  of 
104,000.  The  saving  has  been  so  great  as  to  meet  the  increasing 
demands  of  the  city  and  district  for  eleven  years. 

"  The  change  to  constant  service  has  already  yielded  nearly  a 
quarter  of  a  million  of  money  (^"250,000),  and  the  ultimate  saving 
to  the  rate-payers,  when  the  7,000,000  gallons  per  week  yet  un- 
sold are  absorbed,  will  be  ^50,000  per  annum." 

The  conditions  under  which  this  system  of  waste  detection 
has  been  tried  in  Glasgow  correspond  more  nearly  with  those 
existing  in  Boston  and  other  American  cities,  than  do  those  of 
other  European  cities  where  the  system  has  been  used.  The 
supply  furnished  is  constant  and  ample,  and  the  proportion  of 
water  fittings  to  the  population  is  larger  than  is  common  in  most 
European  cities. 

The  following  table  (Brackett)  shows  the  results  obtained  in 
Glasgow  from  an  inspection  similar  to  the  one  made  in  Boston : 


TABLE  XXVIL— WASTE  WATER  INSPECTION  IN  GLASGOW. 


J) 

1 

y 

fci 

GALLONS  PER  HEAD  PER  DAY. 

li 

h  K 

At  starting  of  meters. 

After  first  three  inspec- 
tions. 

C£   3 

K  ^ 

«    U) 

«  *   . 

I 

Id  2 

ffl   Q 

p 

ili 

3  <ft  U 

Total. 

Night  rate 
per 

Total. 

Night  rate  • 
per 

s 

£ 

^ 

24  hours. 

21  hours. 

I 

9 

14,972 

25.8 

71.0 

54-0 

40.9 

21  .  1 

II 

6 

10,002 

22-4 

79.0 

72.2 

50-4 

33-o 

III 

3 

4,986 

35-4 

73-7 

62.4 

44.2 

21.7 

IV 

6 

7,629 

30.6 

79.0 

57-o 

50.5 

24.8 

V 

7 

9.815 

37-8 

55-1 

36.8 

37-7 

17-3 

VI 

8 

12,614 

39-7 

37-2 

29-5 

27.1 

17-8 

VII 

2 

4,132 

25-5 

45-5 

30.6 

41.9 

25.8 

VIII 

3 

6,306 

37-1 

44.9 

27-5 

33-6 

I5-I 

IX 

4 

7,821 

32.1 

44.9 

31-7 

30.8 

15-2 

X 

2 

3,012 

34-6 

44.2 

33-4 

25-0 

12.8 

Totals  and 

averages. 

50 

81,289 

30.6 

55-8 

45-2 

38.4 

21.0 

The  results  of  a  trial  of  the  Deacon  system  on  a  portion  of 


QUANTITY  AND   WASTE. 


2O I 


the  water  service  of  the  city  of  Boston,  Mass.,  are  shown  in  the 
following  table  (Brackett). 

TABLE  XXVIII. — WASTE  WATER  INSPECTION  IN  BOSTON,  MASS. 


ii 

GALLONS  PER  HEAD  PER  DAY. 

td  O 

PERCENTAGE  OF 

i 

*-  uo 

After  two  or  three 

REDUCTION. 

NUMBER 

OF 

K  ft* 

Before  inspection. 

inspections. 

SECTION. 

if 

III 

Total. 

Night 
rate  per  24 

Total. 

Night 
rate  per  24 

On  total. 

On  night 

A 

a.   i 

hours. 

hours. 

I 

2,810 

9-2 

53-5 

39-1 

26.4 

10.6 

50.7 

72.9 

I  and  i  A 

3,675 

9.1 

52. 

39-0 

34-1 

13-7 

34-4 

64.9 

2 

2,170 

8.1 

49-9 

33-1 

36.7 

13.2 

26.5 

60.6 

3 

2,030 

6.2 

71.8 

43-2 

45-1 

2O.  2 

37-2 

53-2 

4 

i,  880 

5.9 

68.4 

42.2 

47  8 

22.3 

30.1 

47.2 

5 

1,790 

5-9 

72.7 

53-3 

47.8 

17.8 

34-3 

66.6 

6 

1,875 

7.2 

60. 

44.6 

35-3 

I5-I 

41.2 

66.1 

7 

2,540 

6.8 

55-2 

31-9 

39-6 

19.2 

28.3 

39-8 

8 

2,400 

6.6 

55- 

40.8 

37-9 

I8.5 

3I-I 

54-7 

9 

2,150 

5-5 

62.9 

40.1 

36-2 

13-7 

42.4 

65-8 

10 

1,790 

5.6 

52-3 

28.1 

46.  i 

I8.7 

II.  9 

33-4 

ii 

2,800 

6.5 

43-7 

17-5 

25-7 

9-5 

41.2 

45-7 

12 

2,300 

7.6 

80.4 

55-2 

31.2 

12.5 

61.2 

77-4 

Averages 

6.86 

58.5 

37-5 

37-7 

15.8 

35-6 

57-9 

From  the  above  it  appears  that  on  the  whole  district  covered 
by  the  inspection,  containing  a  population  of  21,760  persons,  the 
average  daily  consumption  was  reduced  from  58.5  to  37.7  gallons, 
a  saving  of  35.6  percent,  or  20.8  gallons  for  each  person  supplied, 
while  the  night  rate  was  reduced  from  37.5  to  15.8  gallons  per 
head  per  day,  a  saving  of  58  per  cent.  The  Boston  experiments 
being  continued  for  a  short  time  only,  seem  to  have  cost  more 
than  the  value  of  the  water  saved  ;  this  is  not  the  case  where  the 
system  forms  a  part  of  the  regular  operation  of  the  water  works. 

The  Cincinnati  Board  of  Public  Works  use  a  device  invented 
by  Mr.  Thomas  J.  Bell,  the  Assistant  Superintendent  of  the 
Water  Works,  which  takes  advantage  of  a  fact  long  known, 
namely,  that  it  is  possible  to  detect  a  leak  by  taking  advantage 
of  the  conduction  of  the  sound  caused  by  that  leak  through  the 

J  o 

metal  pipes  by  some  metallic  connection,  to  the  ear.  Mr.  Bell's 
device  consists  of  a  diaphragm  inclosed  in  a  hollow  piece  of 
wood,  shaped  like  a  telephone,  and  about  the  same  size.  A  piece 
of  iron  extends  through  the  middle  of  the  neck  of  the  "  detect- 
or/' one  end  projected  and  threaded,  and  the  other  communicat- 
ing with  the  diaphragm.  A  threaded  hole  is  bored  in  the  top 


202 


WATER   SUPPLY. 


of  the  key  used  to  turn  water  on  and  off  at  the  cocks  on  the  edge 
of  the  pavements,  and,  when  it  is  desired  to  make  a  test,  the  de- 
tector is  screwed  into  the  top  of  the  key  and  the  ear  applied  to 
the  detector.  The  least  leakage  or  the  smallest  stream  running 
from  a  hydrant  can  be  distinctly  heard.  Inspections  are  made  at 
night. 

A  waste-water  indicator,  invented  by  Mr.  Benj.  S.  Church, 
resident  engineer  of  the  Croton  aqueduct,  N.  Y.,  is  thus  de- 
scribed in  The  Sanitary  Engineer,  to  the  publisher  of  which  we 

are  indebted  for  the  use 
of  the  cut  (Fig.  52). 

"  The  device  consists 
of  a  pressure  gauge,  with 
arrangements  for  attach- 
ing it  to  the  pipe  through 
which  water  is  suspected 
of  leaking.  Its  most  ex- 
tensive application  is  de- 
signed to  be  to  service 
pipes  from  street  mains 
to  houses.  For  this  pur- 
pose, a  special  stop-cock 
is  placed  on  the  service 
pipe  under  the  sidewalk 
instead  of  the  ordinary 
kind,  and  from  it  a  pipe 
or  hollow  stem,  instead  of 
a  solid  rod,  runs  up  to  the 
stop-cock  box.  The  shank 
of  the  key,  also,  is  hollow, 
and  has  a  pressure  gauge 
attached  at  the  top.  By 
means  t  of  a  coupling, 
turned  by  a  wheel  at  its  top  (shown  just  below  the  handles  of 
the  key  on  either  side  of  the  gauge),  an  air  tight  connection  is 
made  between  the  stem  and  the  key.  When  the  cock  is  closed 
(by  turning  the  cross-arms,  and  with  them  the  gauge,  which  is 
fastened  to  them),  a  small '  port '  in  the  stopcock  plug  establishes 
a  connection  between  the  street  main  and  the  gauge ;  the  air  of 
the  stem  is  compressed,  and  the  hand  on  the  gauge  indicates  the 


FIG.  52. — CHURCH'S  DETECTOR. 


QUANTITY   AND   WASTE.  203 

hydrostatic  pressure  on  the  main.  By  turning  the  plug  to  another 
position,  a  second  '  port  '  is  opened,  allowing  the  water  to  flow 
through,  if  there  be  any  escape  from  the  pipes  in  the  house.  If 
that  be  the  case,  the  gauge  will  indicate  a  diminished  pressure, 
depending  on  the  amount  of  the  discharge.  The  plug  can  also 
be  turned  to  a  third  position,  leaving  it  open  to  the  house  and 
closed  against  the  street.  By  this  means  the  approximate  height 
of  the  leak  (if  such  is  found)  is  ascertained.  The  exact  position 
of  the  ports  is  indicated  on  a  scale  with  vernier,  which  slides  up 
and  down  the  coupling,  to  be  clamped  at  the  level  of  the  side- 
walk for  convenience  in  making  reference  marks  thereon.  The 
gauge  is  said  to  indicate  a  flow  of  five  gallons  an  hour,  and  '  re- 
veal the  least  leakage  even  to  the  size  of  a  pin-hole/  The  ap- 
paratus may  also  be  applied  to  street  mains  to  detect  leaks  in 
them."* 

The  second  general  method  for  checking  waste  is  the  universal 
introduction  of  meters.  There  can  be  no  question  of  the  justice 
and  propriety  of  measuring  the  water  used  for  manufacturing 
purposes  or  in  hotels  and  other  large  establishments.  It  is,  how- 
ever, objected  that  the  adoption  of  meters  for  private  dwellings 
will  cause  an  injurious  economy  in  the  use  of  water  among  the 
very  class  of  the  population  where  it  is  important  that  water 
should  be  used  freely.  This  objection  is  obviated  to  a  great 
extent,  at  least,  in  some  places  where  meters  are  employed,  by 
fixing  a  minimum  tax — to  be  paid  by  all  water-takers — which 
shall  cover  a  certain  quantity,  based  on  a  reasonable  estimate  of 
domestic  needs.  Water  used  in  excess  of  this  quantity  is  paid 
for  by  measurement,  and  special  arrangements  may  be  made  for 
tenement  houses  and  the  dwellings  of  the  very  poor.  It  is 
further  said  that  the  cheaper  meters  are  not  very  reliable,  that 
it  is  often  possible  to  pass  a  considerable  amount  of  water  with- 
out its  being  registered,  provided  the  water  be  allowed  to  flow 
slowly,  and  that  the  meters  are  continually  needing  repairs  and 
giving  rise  to  dissatisfaction  and  complaint  on  the  part  of  the 
water-takers. 

Meters  are  in  very  general  use  in  Providence  and  Pawtucket, 
R.  I.,  and  in  Fall  River,  Mass.,  having  been  introduced  with  the 
water  supply:  Providence,  with  9,780  services  has  4,816  meters, 
and  consumes  36.3  gallons  per  head  of  population ;  in  Fall  River 

*  The  Sanitary  Engineer,  January  18,  1883. 


2O4  WATER  SUPPLY. 

60  per  cent,  of  the  services  are  metered,  and  the  consumption  is 
30.1  gallons  per  head.  The  introduction  of  meters  is,  of  course, 
much  more  easy  with  new  works  than  with  works  already  estab- 
lished. No  statistics  have  come  under  the  author's  observation 
with  reference  to  the  matter  of  repairs  in  those  American  cities 
where  the  use  of  meters  is  anything  like  general.  The  following 
statistics  are  compiled  from  German  sources : 

In  Magdeburg  it  was  decided  in  1879  to  introduce  meters 
universally,  and  the  water  rate  was  fixed  at  33  marks  (say  $8.00) 
per  house  for  any  amount  up  to  300  cubic  meters  per  annum 
(about  215  U.  S.  gallons  per  day).  Above  this  amount  the 
charge  was  made  at  the  same  rate,  i.  e.,  1 1  pfennige  per  cubic 
meter.  The  introduction  of  meters  was  decided  upon  almost  as 
a  necessity,  but,  according  to  subsequent  official  reports,  has 
been  in  every  way  successful.  At  the  close  of  the  year  1880 
there  were  2,792  meters  in  use.  During  the  year  168  meters 
had  required  repairs,  and  70  had  been  tested  at  the  request  of 
consumers.  The  meters  are  all  tested  before  introduction,  and  a 
record  kept  for  future  comparison.  In  Berlin  meters  are  in  uni- 
versal use.  Eighty-two  per  cent  of  the  water  supplied  is 
measured  and  paid  for ;  the  remainder  includes  what  is  used  for 
flushing  the  pipes,  for  extinguishing  fires,  for  sprinkling  streets, 
etc.,  and  also  loss  by  leakage.  Of  the  15,853  meters  in  use  in 
1 880-8 1,  2,093,  or  13.2  per  cent,  were  removed  for  more  or  less 
serious  defects,  the  number  registering  incorrectly  or  not  at  all 
being  1,580,  or  ten  per  cent  of  the  whole  number  in  use.  In 
Breslau  the  number  of  meters  in  use  in  1 880-81  was  5,141  ;  of 
these,  during  the  year,  1,085  were  tested  by  request  of  the  con- 
sumer or  at  the  instance  of  the  inspector.  Of  the  1,085  tested, 
740  were  found  to  need  repairs  of  some  sort,  406  (i.  e.,  7.9  per 
cent)  registered  incorrectly  or  not  at  all.  It  should  be  said  that 
the  error  in  registering  is  generally  to  the  benefit  of  the  con- 
sumer. 

Of  the  methods  indicated  to  check  waste,  local  considerations 
must  determine  which  shall  be  adopted.  If  a  city  "  has  at  its 
disposal  150  million  gallons  daily  for  a  population  which  does 
not  consume  30  millions,"  as  is  stated  to  be  now  the  case  in  Balti- 
more, Md.,  there  is  certainly  no  occasion  for  introducing  meters 
at  all ;  but  in  places  where  the  available  water  is  limited  in 
quantity,  or  where,  without  economy,  the  existing  supply  is 


QUANTITY  AND  WASTE.  205 

likely  to  prove  insufficient  in  the  immediate  future,  or  in  places 
where  the  rates  are  of  necessity,  high,  the  introduction  of  meters 
would  be  advisable.  The  waste  in  Northern  cities  during  the 
winter  is  enormous,  as  it  is  very  common  to  leave  the  faucets 
open  during  the  night,  in  order  to  prevent  freezing.  This  cold 
weather  waste  can  never  be  completely  stopped  until  property 
owners  are  obliged  to  arrange  their  plumbing  so  that  the  water 
can  be  completely  drawn  from  the  pipes  when  liable  to  freeze. 
By  the  use  of  meters  it  can  be  largely  reduced,  as  the  waste 
would  be  reduced  to  the  minimum  amount  required  to  prevent 
the  pipes  from  freezing,  and  it  would  become  a  question  to  the 
water-taker  whether  it  was  economy  to  waste  water  or  remodel 
his  fixtures. 

Next  in  importance  to  the  special  form  of  waste  just  alluded 
to,  is  that  due  to  defective  or  improper  fixtures.  Such  sources 
of  waste  may  be  readily  detected  by  systematic  inspection, 
and  should  be  controlled  by  municipal  regulation,  as  is  indeed 
done  in  some  cities.  "  Providence,  New  York,  Brooklyn  and 
other  American  cities  license  their  plumbers,  and  to  a  certain 
extent  inspect  the  fixtures  used ;  but  in  English  cities  the  ordi- 
nances and  regulations  are  much  more  rigid  than  those  in  this 
country.  Liverpool,  Manchester,  Glasgow  and  other  English 
cities  test  and  stamp  all  of  the  water  fittings  used.  In  Glasgow, 
during  the  year  1877,  when  this  plan  was  first  adopted,  of  4,369 
fittings  examined,  14.6  per  cent  were  rejected,  while  in  1880,  of 
27,517  examined,  but  3.92  per  cent  were  rejected.  In  the  latter 
city  certain  varieties  of  fittings  are  proscribed.  When  any  of 
these  are  found  wasting  water  twice  during  three  months,  they 
are  removed,  and  their  use  is  not  allowed  at  all  in  new  prem- 
ises. 

"  All  cisterns  are  provided  with  overflow  pipes,  which  are 
brought  outside  the  building  or  made  to  discharge  inside  where 
they  can  be  seen.  The  service  pipes,  except  in  special  cases,  are 
required  to  be  of  lead,  and  their  weight  is  prescribed.  No  pipe 
or  fitting  can  be  covered  until  inspected,  to  see  that  it  conforms 
to  the  regulations. 

"  Water-closets  and  urinals  are  not  allowed  to  be  supplied 
direct  from  the  service  pipe,  but  must  be  supplied  from  cisterns, 
so  constructed,  that  in  water-closets  not  more  than  two  gallons 
can  be  used  at  a  single  flush,  and  in  urinals  not  more  than  i£ 


206  WATER  SUPPLY. 

gallons,  and  so  that  they  cannot  be  made  to  flow  continuously 
either  by  intention  or  neglect. 

"  The  adoption  of  the  above  or  similar  regulations  in  Ameri- 
can cities,  -while  not  in  the  least  curtailing  the  legitimate  use  of 
water,  would  be  the  means  of  preventing  a  very  large  proportion 
of  the  present  enormous  amount  of  willful  and  useless  waste."  * 

In  view  of  the  difficulty  of  supplying  large  cities  with  water 
against  which  no  complaints  can  arise,  the  question  is  often 
raised  whether  it  is  not  advisable,  in  some  cases,  to  introduce  a 
double  supply.  As  the  author  has  remarked  elsewhere  :f  "  It  is 
true  that  for  many  purposes,  as  for  extinguishing  fires  and  for 
sprinkling  streets,  a  water  would  answer  which  would  not  be 
suitable  for  drinking,  and  such  a  supply  might  in  many  cases  be 
easily  procured,  while  to  procure  an  abundance  of  water  well 
suited  for  drinking  would  involve  a  large  outlay.  To  the  double 
system  there  is  no  (sanitary)  objection,  if  the  poorer  water  can 
be  drawn  only  from  street  hydrants,  which  are  under  municipal 
control ;  but  it  is  not  practicable  to  supply  two  sorts  of  water  to 
private  dwellings,  with  any  security  that  the  distinction  between 
them  will  be  regarded ;  no  domestic,  and  indeed  no  average  in- 
habitant, will  fail  to  use  for  all  purposes  that  water  which  is  most 
handily  obtained,  unless,  indeed,  it  be  actually  repulsive  to  the 
taste."  It  should  be  said,  moreover,  that  the  introduction  of  a 
second  (inferior)  water,  where  works  already  exist,  would  often 
prove  nearly  or  quite  as  expensive  as  the  extension  of  the  exist- 
ing works  and  the  increase  of  the  supply  of  water  fit  to  drink. 

Conduits  and  Distribution  Pipes. 

Where  the  source  of  supply  is  at  a  considerable  distance,  the 
water  is  usually  carried  by  gravity  in  brick  or  other  masonry  con- 
duits to  a  storage  or  distributing  reservoir.  Open  canals  are  dis- 
advantageous, especially  on  account  of  the  liability  of  pollution, 
but  also  as  giving  opportunity  for  considerable  changes  of  tem- 
perature and  for  vegetable  growths.  The  water  in  passing 
through  a  long  conduit  has  some  action  on  the  mortar  or  cement, 
and  may  become  slightly  harder  ;  generally,  however,  the  volume 
of  water  is  so  great  that  there  is  very  little  perceptible  effect. 
E.xcept  in  this  respect,  the  water  undergoes  almost  no  change. 

*  Brackett,  loc.  dt.  \  Buck's  Hygiene,  vol.  i.  p.  215. 


CONDUITS  AND   DISTRIBUTION  PIPES.  2O/ 

Even  the  change  of  temperature  in  a  properly  covered  conduit 
with  constant  flow  is  small,  Thus,  Kerner  found,  in  the  hottest 
days  of  the  summer  of  1875,  that  the  water  of  the  Frankfort 
supply  increased  in  temperature  from  9°  C.  to  only  10°  C.,  in 
flowing  from  the  source  to  the  main  reservoir,  a  distance  of  82 
kilometers.  In  passing  through  the  city  mains,  a  further  distance 
of  six  kilometers,  the  temperature  increased  2°. 75  C.*  (Compare 
page  93.)  Where  the  source  of  supply  is  a  river  or  pond,  a  con- 
siderable growth  of  the  fresh-water  sponge  is  often  found  on  the 
walls  of  the  conduit  for  some  distance.  For  this  and  other 
reasons,  such  conduits  should  be  subjected  to  periodical  cleansing, 
if  inspection  shows  it  to  be  necessary. 

The  distances  of  the  sources  of  supply  of  various  cities  is  as 
follows : 

Altenburg  (springs) 15.5  miles.  Munich  (springs) 24.9  miles. 

Danzig  (springs) 12.4     "  Paris  (River  Dhuis) 81.4     " 

Frankfort  a.  M.  (springs). ..  52.        "  Paris  (River  Vanne) 107.2     " 

Glasgow  (lake) 36.        "  Vienna  (springs) 60.3     " 

Gotha  (springs) 20.5     " 

Boston  (Lake  Cochituate) . . .   16.       "          New  York  (Croton  River)  40.6     " 

From  the  distributing  reservoir,  or  directly  from  the  source  of 
supply,  the  water  passes  into  the  main  distribution  pipes,  which 
are  usually  of  cast  iron.  Although  there  are  some  waters  which 
experience  has  shown  to  have  almost  no  action  on  cast  iron,  with 
most  waters  the  pipes  soon  begin  to  rust.  The  rust  often  begins 
at  numerous  isolated  points,  or  nuclei,  forming  "tubercles," 
which  increase  in  size,  become  merged  together  and  finally — aided 
by  the  collection  of  sediment  from  the  water — nearly  choke  the 
pipe.  The  presence  of  iron  in  the  water,  either  in  solution  or  in 
suspension,  can  hardly  be  regarded  as  deleterious  to  health,  but 
the  water  is  sometimes  rendered  unfit  for  washing  and  cooking. 
The  presence  and  growth  of  the  deposit  of  iron-rust,  has,  how- 
ever, a  very  serious  effect  on  the  flow  of  the  water,  and  it  be- 
comes necessary  to  remove  the  deposit  by  scraping  the  inside 
of  the  pipes.  Several  special  tools  have  been  devised  for  this 
purpose.  The  following  tables  (Tables  XXIX  and  XXX)  will 
show  the  effect  of  the  accumulation  of  rust  in  diminishing  the 

*  Wolffhugel :  Wasserversorgung,  p.  227. 


208 


WATER   SUPPLY. 


capacity  of  the  pipe  and  the  flow  of  water  :  they  are  the  results 
of  observations  made  in  Aberdeen,  Scotland.* 

TABLE  XXIX. — DIMINUTION  OF  AVAILABLE  CAPACITY  OF  CORRODED   PIPES. 


No. 

AGE  OF  PIPE. 

CHARACTER. 

INTERNAL 
DIAMETER. 

AMOUNT  OF 
RUST  PER  LINE- 
AR YARD. 

CAPACITY  OF 

CLEAN  PIPE    PER 

LINEAR  YARD. 

PERCENTAGE  OF 
SPACE  OCCUPIED 

BY  RUST. 

Years. 

Inches. 

Cu.  Inches. 

Cu.  Inches. 

I 

2O 

Uncoated. 

3 

63.84 

254.44 

25.0 

2 

29 

3 

86.94 

254.44 

34-1 

3 

38 

3 

110.44 

254.44 

43.4 

4 

29 

4 

182.37 

452.37 

40.3 

5 

22 

4 

244-37 

452.37 

54-o 

6 

14 

5 

180. 

706.86 

25.4 

7 

15 

Coated. 

7 

190. 

1,385.42 

13-7 

8 

15 

' 

10 

240. 

2,827.44 

8.4 

9 

40 

15 

1,320. 

6,361.74 

20.7 

TABLE  XXX. — DISCHARGE  FROM  CORRODED  PIPES. 


APPROXIMATE 

HEAD  IN  FEET. 

DISCHARGE  PER  MINUTE. 

DIAM- 

AGE 

AMOUNT  OF  COR- 

No. 

ETER  OF 

OF 

ROSION  PER  LINEAR 

Before 

After 

PIPE. 

PIPE. 

YARD. 

Before 

After 

Cleaning. 

Cleaning. 

Cleaning. 

Cleaning. 

Inches. 

Years. 

Cu.  Inches. 

Imp.  Gallons 

Imp.  Gallons 

I 

3 

29 

86.99 

42 

47 

47 

143 

2 

3 

29 

93- 

54 

56 

79 

188 

3 

3 

29 

93- 

70 

74 

143 

200 

4 

3 

32 

190. 

77 

82 

16 

150 

5 

3 

32 

190. 

72 

72 

H5 

I87 

6 

3 

26 

80. 

56 

62 

35 

220 

7 

3 

26 

88. 

36 

43 

65 

130 

8 

4 

29 

100. 

40 

45 

69 

H5 

9 

4 

29 

IOO. 

38 

42 

125 

107 

These  results  are  the  average  gaugings  of  five  different  trials  taken  once  a  week 
on  the  same  day. 

On  account  of  the  action  of  most  waters  on  cast-iron  pipes  it 
is  usual  at  the  present  time  to  protect  the  surface  in  some  way 
from  corrosion.  The  process  commonly  employed  is  that  devised 
by  Dr.  R.  Angus  Smith :  the  newly  cast  pipes,  which  must  be 
free  from  rust,  are  heated  to  a  temperature  of  some  500°  Fahr., 
and  then  dipped  perpendicularly  into  a  hot  bath  of  coal-tar 
pitch  mixed  with  a  small  proportion  of  heavy  coal  oil.  In  this 
bath  they  are  allowed  to  remain  for  a  short  time  and  then  with- 
drawn. The  coating  thus  formed  is  firmly  coherent  and  is  unob- 

*  M.  B.  Jamieson  :  The  internal  corrosion  of  cast-iron  pipes.  Proc.  Inst.  Civ. 
Eng.  Gr.  Br.,  Ixv  (1881),  p.  323. 


CONDUITS   AND   DISTRIBUTION   PIPES.  2OQ 

jectionable  from  a  sanitary  point  of  view.  It  does  not  afford 
absolute  protection  against  rust,  but  it  delays  and  diminishes  the 
action  of  the  water  to  a  great  extent.  The  first  line  of  pipes  of 
this  description  laid  in  this  country  was  laid  in  Boston  in  1858. 
In  1876-77  some  of  these  (20  in.)  pipes  were  removed.  "As 
they  were  taken  up  their  condition  was  observed.  Their  inner 
surfaces  were  not  entirely  free  from  tuberculation,  but  were  very 
much  more  so  than  are  the  surfaces  of  uncoated  pipes  in  this 
city  after  they  have  been  laid  but  a  few  years.  The  tubercles 
were  isolated,  and  were  not  in  sufficient  numbers  or  of  sufficient 
size  to  very  materially  interfere  with  the  capacity  of  flow  of  the 
pipes.  They  were  very  easily  removed — more  easily  than  from 
uncoated  pipes — seeming  to  have  very  little  hold  upon  the  tar 
surface. 

"  Upon  cleaning  off  the  surface  under  a  tubercle  one  would  at 
first  suppose  there  had  been  simply  a  deposit,  that  no  action  had 
been  had  either  upon  the  iron  or  upon  the  coating ;  but  a  more 
careful  examination  would  show  that  under  the  center  of  the 
tubercle  a  portion  of  the  iron,  from  the  size  of  a  pin  head  to  that 
of  a  small  pea,  had  been  transformed  into  a  black  substance  that 
could  be  easily  cut  with  a  knife,  and  had  the  appearance  of  plum- 
bago. The  inference  drawn  from  the  general  appearance  of  the 
pipes  was  that  they  would  have  lasted  for  an  indefinite  period."  * 

Some  time  since  Professor  Barff,  of  London,  proposed  to 
protect  articles  of  iron,  among  other  things  water  pipes,  from 
corrosion,  by  covering  them  with  an  artificial  coating  of  the  black 
oxide  of  iron.  The  coating  is  produced  by  exposing  the 
metal  to  superheated  steam  at  a  high  temperature,  and  when 
once  formed  it  protects  the  iron  from  atmospheric  and  other 
agencies  which  would  corrode  it.  The  process  has  been  some- 
what modified  and  is  now  known  as  the  Bower-Barff  process,  and 
promises  to  become  a  practical  and  valuable  means  of  protecting 
cast-iron  pipes.  Some  wrought-iron  pipes  of  this  description 
have  been  introduced  as  service  pipes  in  Altona,  and  probably 
elsewhere,  but  it  is  too  soon  for  definite  statements  as  to  their 
durability. 

Cast-iron  pipes  are  usually  connected  by  the  hub  and  spigot 
joint ;  the  joints  are  first  packed  with  tow  or  jute  and  then 

*  First  Annual  Report  of  the  Boston  Water  Board.  City  Document  No.  57. 
Boston,  1877. 

14 


2  IO  WATER  SUPPLY, 

melted  lead  is  run  in  and  driven  up  firmly.  It  has  been  found 
that  the  tow  sometimes  gives  an  unpleasant  taste  to  the  water, 
and  the  Rivers  Pollution  Commission  recommended  that  the 
joints  of  the  larger  mains  should  be  pointed  up  with  Portland 
cement  on  the  inside  to  prevent  the  water  from  coming  in  con- 
tact with  the  tow. 

The  sediment  which  accumulates  in  the  pipes,  especially  in 
low-lying  districts,  although  it  has  generally  a  rusty  appearance, 
is  not  simply  iron  rust  from  the  pipes.  With  the  iron  rust  there 
is  always  more  or  less  earthy  matter,  and  sometimes  the  sedi- 
ment contains  a  large  proportion  of  vegetable  organisms,  such 
as  the  CrenothriXy  already  described.  The  following  results  were 
obtained  from  the  analysis  of  the  rust  in  the  Aberdeen  pipes 
already  referred  to  : 

From  uncoated  4-in.  Pipe  From  coated  to-in.  Pipe 

21  years  in  use.  15  years  in  use. 

Organic  and  volatile  matter 16.62  18.05 

Sulphuric  acid  (SO3) 0.60  1.08 

Phosphoric  acid Slight  trace  trace. 

Magnetic  oxide  of  iron 32.47  0.36 

Peroxide  of  iron 9.04  37-55 

Insoluble  sandy  matter 41.27  42-78 

Lime trace  o.  18 

Wrought-iron  pipes,  coated  with  cement  inside  and  out,  have 
been  sometimes  used,  generally  from  motives  of  economy.  They 
are  made  by  rolling  up  sheet  iron  and  riveting  the  edges  of  the 
sheet  together  as  shown  in  Fig.  54.  A  longitudinal  rib  is  some- 
times employed  as  shown  in  Fig.  53-  The  lengths  of  pipes  may 
be  telescoped  together,  but  are  usually  connected  by  means  of 
an  iron  sleeve,  filled  in  with  cement.  The  durability  of  the 

pipes  is  very  dif- 
ferent in  different 
localities,  owing 
mainly  to  dif- 
ference in  the 
quality  of  the 
workmanship. 
Where  the  pipes 

have  been   made 
FIG.  53.  FIG.  54.  j. 

under  the    direc- 
tion of  the  water  department,  by  day  labor,  they  have  sometimes 


CONDUITS  AND   DISTRIBUTION   PIPES.  211 

proved  very  satisfactory,  but  where  the  work  is  done  by  con- 
tract it  is  difficult  always  to  obtain  the  best  results. 

In  the  extreme  West,  wrought-iron  pipes  are  used  for  con- 
veying water  for  hydraulic  operations  and  for  purposes  of  water 
supply,  sometimes  under  a  very  great  head.  Water  is  conveyed 
to  Virginia  City,  Nevada,  through  such  a  main,  the  maximum 
thickness  of  which  is  0.34  inch,  and  which  is  exposed  in  some 
parts  of  its  length  to  a  pressure  of  1,800  feet  head  of  water.  The 
pipes  are  coated  with  asphaltum  to  prevent  rusting. 

Wooden  pipes,  generally  bored  logs,  have  been  used  more  or 
less  for  conveying  water,  and  are  still  employed  in  some  sections 
of  the  country.  Detroit  had  at  one  time  130  miles  of  wooden 
pipe,  and  \y2  miles  were  laid  in  1880.  The  logs  used  are  sound 
green  tamarack,  not  less  than  6  inches  in  diameter  and  8  feet 
long.  The  joints  are  covered  with  iron  thimbles,  and  the  pipes 
last  for  1 6  years  or  more  and  cost  (or  did  cost)  only  about  one- 
fifth  as  much  as  iron. 

Service  pipes. — The  service  pipes  for  house  distribution  in 
connection  with  a  public  water  supply  are  generally  of  lead,  this 
metal  being  employed  on  account  of  the  facility  with  which  it 
may  be  worked.  Lead  pipes  are  also  sometimes  used  for  convey- 
ing well  or  spring  water  to  individual  residences.  Various  waters 
act  very  differently  upon  lead,  some  corroding  it  rapidly,  others 
only  to  a  very  slight  extent,  under  similar  circumstances.  The 
cause  of  the  corrosion  is  to  be  sought  in  the  dissolved  oxygen, 
of  which  all  waters  contain  more  or  less,  and  in  certain  saline  sub- 
stances the  presence  of  which  determines  a  more  violent  action. 
It  is  generally  felt,  for  instance,  that  the  presence  of  nitrates, 
nitrites,  and  ammoniacal  salts  increases  the  action  of  water  on 
lead,  while  carbonates,  sulphates,  and  notably  phosphates,  hinder 
such  action ;  but  while  certain  general  statements  may  be  truth- 
fully made  as  the  result  of  laboratory  experiment  and  from  the 
analysis  of  waters  whose  action  on  lead  has  been  learned  by 
experience,  it  is  a  rather  hazardous  thing  for  a  chemist  to  pre- 
dict, a#rwri,what  will  be  the  effect  of  a  particular  water  on  lead 
pipe  under  the  conditions  of  ordinary  practice.  Next  to  no  value 
attaches  to  experiments  made  by  immersing  strips  of  sheet  lead 
in  open  or  closed  vessels  containing  the  water  under  examina- 
tion. In  actual  practice,  many  waters  which  would  be  pro- 
nounced dangerous  on  the  strength  of  such  experiments,  prove 


212  WATER  SUPPLY. 

entirely  harmless.  The  pipes  very  soon  become  covered  with  a 
naturally  formed  protective  coating  of  difficultly  soluble  com- 
pounds of  lead ;  and  after  a  slight  initial  action,  corrosion  prac- 
tically ceases  if  the  pipes  are  kept  constantly  filled. 

If  it  is  felt  necessary  to  make  or  to  have  made  preliminary 
laboratory  experiments,  they  should  be  made  by  imitating  as 
nearly  as  possible  the  conditions  of  actual  practice,  and  sufficient 
time  should  be  employed.  The  following  extract  from  the  report 
on  the  examination  of  a  soft  surface  water  (where  the  time  at 
disposal  was  somewhat  limited),  will  serve  as  an  example :  * 

"A  coil  of  100  feet  of  new  one-quarter  inch  lead  pipe  was 
taken  and  filled  with  the  water  under  examination.  The  pipe 
held  64  cubic  inches  of  water,  and  the  surface  of  lead  was  equal 
to  about  900  square  inches.  The  water  was  allowed  to  remain 
in  the  pipe  for  50  hours  and  then  removed,  a  fresh  supply  being 
introduced  without  allowing  the  air  to  come  into  contact  with 
the  inside  surface  of  the  pipe.  The  water  as  drawn  was  quite 
turbid,  from  the  presence  of  the  oxycarbonate  of  lead,  and  was 
found  to  contain  (the  lead  being  calculated  as  metallic  lead)  : 

METALLIC  LEAD. 
Parts  per  100,000.    Grains  in  U.  S.  gallon. 

In  solution 0.055  0.032 

In  suspension 1-257  °-733 

Total.. 1.317  0.765 

"  At  the  end  of  70  hours  the  water  in  the  pipe  was  drawn  out 
and  found  to  contain  : 

METALLIC  LEAD- 
Parts  per  100,000.    Grains  in  U.  S.  gallon. 

In  solution 0.573  0.334 

In  suspension 0.137  o  080 

Total 0.710  0.414 

"The  pipe  was  then  thoroughly  washed  from  any  loosely 
adhering  coating  by  allowing  a  rapid  stream  of  Cochituate  water 
to  flow  through  for  some  time.  The  Cochituate  water  was  then 
displaced  by  the  water  under  examination,  and  this  water  was 
allowed  to  remain  in  the  pipe  for  30  hours.  This  water,  when 
drawn,  contained,  both  in  solution  and  suspension,  o.  157  part  of 
metallic  lead  in  100,000,  or  0.092  grain  to  the  U.  S.  gallon.  The 

*  Report  on  the  Waters  of  Flax  Pond,  made  to  the  City  Council  of  Chelsea,  Mass., 
1875- 


SERVICE   PIPES.  213 

amount  in  suspension  was  not  determined  separately,  as  there 
was  no  very  considerable  quantity  visible  to  the  eye.  A  fresh 
portion  was  allowed  to  remain  in  the  pipe  for  40  hours,  and  then 
contained  in  solution  and  suspension  0.184  part  in  100,000,  or 
o.  107  grain  to  the  U.  S.  gallon." 

At  the  conclusion  of  the  experiment  the  action  on  the  lead 
had  not  ceased,  even  practically,  but  it  had  diminished  very  much, 
and  there  was  no  doubt  that,  in  practice,  the  water  would  act 
very  slightly  on  the  pipes  when  in  continuous  use,  as  has  proved 
to  be  the  case  in  Boston,  New  York,  Glasgow,  Manchester,  and 
many  other  places  where  the  question  has  been  discussed. 

It  may  be  said  that,  while  with  most  waters  the  action  on  the 
lead  practically  ceases,  it  probably  never  ceases  absolutely.  The 
water  of  Lake  Cochituate,  as  supplied  in  Boston,  Mass.,  through 
lead  pipes,  always  contains  traces  of  lead  in  solution.  The 
amount  of  lead  taken  up  by  the  water  in  passing  through  some 
150  feet  of  pipe  which  had  been  in  use  for  some  years,  was  found 
to  be  only  0.03  part  in  100,000,  or  less  than  0.02  grain  in  the 
U.  S.  gallon.  Water  which  is  allowed  to  remain  in  the  pipe  for 
some  time,  or  is  drawn  from  the  hot-water  faucets,  may  contain 
as  much  as  o.i,  or  even  0.2  part  in  100,000  (from  0.06  to  o.  12 
grain  in  the  gallon),  and  wherever  lead  distribution  pipes  are  in 
use,  it  is  safer  always  to  run  to  waste  enough  water  to  clear  the 
pipes,  and  never  to  use,  for  drinking  or  for  cooking,  water  which 
has  passed  through  the  pipes  while  hot.  A  similar  precaution 
should  be  used  in  the  case  of  new  pipes :  the  water  should  be 
wasted  intermittently  but  freely  for  a  number  of  days.  There  is 
great  difference  in  the  susceptibility  of  different  persons  to  lead 
poisoning.  It  is  thought  that  as  little  as  one-fortieth  of  a  grain  to 
the  gallon  has  caused  sickness,  but  one-tenth  of  a  grain  is  usually 
regarded  as  an  outside  limit.  It  is  doubtful  whether  there  are  any 
well  authenticated  cases  of  lead  poisoning  from  the  use  of  the 
Cochituate  water.*  The  Croton  water  supplied  to  New  York 
city  is  similar  to  the  Boston  water  in  its  action  on  lead,f  although 
at  least  one  case  of  poisoning  has  been  reported,  which  was  sup- 
posed to  be  due  to  the  daily  use  for  some  time  of  water  which 
had  stood  over  night  in  the  pipes.  The  practical  experience  in 


*  See  Report  of  the  Mass.  State  Board  of  Health,  1871. 

f  See  Report  of  the  Metropolitan  Board  of  Health,  New  York,  1869,  p.  420. 


214  WATER   SUPPLY. 

the  use  of  lead  pipe  in  the  cities  mentioned,  and  in  many  others, 
shows  that,  as  a  rule,  there  is  no  danger  in  using  lead  pipes  for 
house  distribution  in  connection  with  a  public  supply. 

The  most  unfavorable  situation  for  lead  pipe  is  as  suction 
pipes  in  wells.  Here  the  corrosion  is  often  very  rapid,  and  it  is 
rendered  more  violent  by  the  fact  that  the  continual  changes  of 
level  expose  a  longer  or  shorter  portion  of  the  pipe  to  the  alter- 
nate action  of  air  arjd»  water.  There  are  instances  enough  of 
lead  poisoning  from  this  cause. 

It  may  be  remarked,  in  this  connection,  that  the  lead  pipe 
now  in  use,  at  least  in  the  eastern  part  of  the  country,  is  much 
inferior  in  strength  and  durability,  and  apparently  more  readily 
corroded  than  that  formerly  in  use.  The  lead  now  in  the  mar- 
ket has  been  desilverized  by  the  zinc  process,  and  this  seems  to 
give  it  a  particular  and  disadvantageous  character. 

Other  materials  besides  lead  are  used  in  the  house  service. 
To  block  tin  or  to  tin-lined  lead  pipes,  if  the  latter  are  properly 
made  and  properly  put  together,  there  is  no  objection  on  sani- 
tary grounds.  The  corrosion  of  the  tin  by  ordinary  waters  would 
result  in  the  formation  of  insoluble  and  harmless  substances.  As 
to  the  suitability  of  the  brass  pipes  which  have  been  proposed, 
there  seems  to  be  no  exact  information.  To  the  various  sorts 
of  "  enameled "  wrought-iron  pipes  which  are  in  the  market 
there  is  no  sanitary  objection.  The  coating  or  enamel  is  gener- 
ally some  preparation  of  coal  tar,  with  or  without  linseed  oil,  and 
this  sort  of  pipe  is  particularly  adapted  for  use  in  wells,  where  a 
portion  of  the  outer  surface  is  exposed  alternately  to  the  action 
of  air  and  water ;  unfortunately,  the  coating  is  not  always  per- 
fect, and  when  the  original  surface  of  the  pipe  is  exposed,  rusting 
begins.  Zinced  or  "  galvanized  "  iron,  as  it  is  called,  is  fully  as  bad 
in  respect  to  rusting.  The  pipes  are  prepared  by  dipping  the 
iron,  previously  well  cleaned  by  means  of  dilute  acid,  into  a  bath 
of  melted  zinc.  The  zinc  adheres  firmly  to  the  surface  of  the 
iron,  and  penetrates  it  to  a  certain  extent,  so  that  we  do  not  deal 
with  a  simple  coating,  such  as  we  have  on  tinned  iron,  or  on  the 
various  forms  of  enameled  pipe.  The  idea  is  that  the  zinc  shall 
protect  the  iron  by  virtue  of  a  galvanic  action  between  the 
two  metals,  and  it  does  protect  the  iron  for  a  time.  When  the 
pipes  are  exposed  to  the  action  of  water,  corrosion  begins  at 
once  :  at  first,  the  action  is  on  the  zinc  alone,  provided  the  origi- 


SERVICE  PIPES.  215 

nal  iron  was  free  from  rust,  and  the  treatment  with  zinc  was 
thorough ;  but  after  a  time  the  zinc  which  remains  will  cease  to 
protect  the  iron,  and  iron  rust  will  begin  to  form.  As  regards 
this  action,  it  is  simply  a  question  of  time.  Water  that  has 
passed  through  zinced  pipes  will  be  found  almost  always,  if  not 
invariably,  to  contain  zinc  compounds,  either  in  solution  or  in 
suspension  ;  the  amount,  however,  is  generally  very  small.  As 
to  the  effect  of  such  water  on  health,  there  is  some  difference  of 
opinion,  but  it  is  generally  believed  that  the  pipes  may  be  safely 
used.* 

One  of  the  best  materials  for  service  pipes  is  wrought  iron 
protected  by  the  Bower-Barff  process,  provided  practical  experi- 
ence justifies  the  theoretical  expectations.  To  such  pipes,  coupled 
without  the  use  of  red  or  white  lead,  there  can  be  nothing  supe- 
rior from  a  sanitary  point  of  view,  and  for  use  in  wells  and  cis- 
terns they  will  supply  a  very  serious  want.  Ordinary  wrought- 
iron  pipes,  although  possessing  many  advantages,  have  the  great 
disadvantage  of  rusting  very  readily  :  the  iron  rust  is  harmless 
but  unsightly  in  drinking  water,  and  may  render  the  water  unfit 
for  culinary  purposes  and  for  use  in  the  laundry. 

*  For  a  full  discussion  of  this  subject,  see  Dr.  Boardman's  paper  in  the  Report  of 
the  Mass.  State  Board  of  Health  for  1874. 


BIBLIOGRAPHY. 


THE  following  list  of  books  makes  no  claim  to  being  exhaustive.  It  includes 
most  of  the  works  referred  to  in  the  preceding  pages,  and  may  perhaps  be 
described  as  a  list  of  such  works  as  would  together  make  a  fair  nucleus  for  a 
library  of  water  supply,  other  than  from  a  strictly  engineering  standpoint. 
Papers  in  periodical  publications  are  not  included. 

I. — WORKS  OF  A  GENERAL  CHARACTER,  MAINLY  FROM  AN  ENGINEERING 

POINT  OF  VIEW. 

Fanning,  J.  T.  :  A  Practical  Treatise  on  Water-Supply  Engineering,  etc. 
8vo,  pp.  650.  Van  Nostrand,  New  York,  1877. 

Grahn,  E.  :  Die  stadtische  Wasserversorgung.  3  vols.  8vo.  Vol.  I.  Mi'm- 
chen,  1877.  [Contains  Statistik  der  stadtischen  Wasserversorgung:  Beschrei- 
bung  der  Anlagen  in  Bau  und  Betrieb.J 

Humber,  William  :  A  Comprehensive  Treatise  on  the  Water  Supply  ot 
Cities  and  Towns,  etc.  Folio,  pp.  378,  and  many  plates.  London,  Crosby, 
Lockwood  &  Co.,  1877.  [An  American  edition  was  published  by  Geo.  H. 
Frost,  Chicago.] 

II. — WORKS  OF  A  GENERAL  CHARACTER,  MAINLY  FROM  A  CHEMICAL  OR 
SANITARY  POINT  OF  VIEW. 

Buck  :  Hygiene  and  Public  Health.  2  vols.  8vo.  New  York,  Wm.  Wood 
&  Co.,  1879. 

Denton,  J.  Bailey  :  Sanitary  Engineering.  8vo,  pp.  429,  with  many  plates. 
Spon,  London,  1877. 

Fischer  :  Die  chemische  Technologic  des  Wassers.  8vo.  Braunschweig, 
1878-80. 

Fodor:  Boden  und  Wasser.     Braunschweig,  1882. 

Great  Britain  :  Report  of  the  Royal  Commission  on  Water-Supply,  with 
Minutes  of  Evidence.  Parliamentary  Documents.  4to.  London,  1869-70. 

Great  Britain  :  Sixth  Report  of  the  Commissioners  appointed  in  1868  to  in- 
quire into  the  Best  Means  of  Preventing  the  Pollution  of  Rivers.  Domestic 
Water  Supply  of  Great  Britain.  410.  London,  1876. 

[This  report  contains,  besides  complete  statistics  of  the  water  supply  of 
Great  Britain,  considerations  and  accounts  of  experiments  on  the  following 
topics  : 

On  the  alleged  self-purification  of  polluted  rivers. 

On  the  propagation  of  epidemics  by  potable  water. 


BIBLIOGRAPHY.  2 1/ 

On  the  alleged  influence  of  the  hardness  of  water  upon  health. 

On  the  superiority  of  soft  over  hard  water  in  cooking. 

On  the  softening  of  hard  water. 

On  the  improvement  of  potable  water  by  nitration. 

On  the  deterioration  of  potable  water  by  transmission  through  mains  and 
service  pipes. 

On  the  constant  and  intermittent  systems  of  water  supply.] 

Lefort,  Jules  :  Traite'  de  Chimie  Hydrologique.  8vo,  pp.  798.  Deuxieme 
Edition.  Paris,  1873. 

Lersch,  Dr.  B.  M.  :  Hydrochemie  oder  Handbuch  der  Chemie  der  natiir- 
lichen  Wasser,  2  Auflage.  8vo,  pp.  718.  Bonn,  1870. 

Parkes,  E.  A.,  M.D.:  Manual  of  Practical  Hygiene.  Fifth  edition.  8vo. 
London  and  Philadelphia,  1878; 

Reichardt :  Grundlagen  zur  Beurtheilung  des  Trinkwassers.  3te  Auflage. 
8vo,  pp.  107.  Jena,  1875. 

Sander,  Dr.  Friedrich :  Handbuch  der  offentlichen  Gesundheitspflege. 
8vo,  pp.  503.  Leipzig,  1877. 

Wolffhiigel  :  Wasserversorgung.  [Aus  dem  Handbuch  der  Hygiene  und 
der  Gewerbekrankheiten,  von  Pettenkofer  und  Ziemssen.  ]  8vo,  pp.  244. 
Leipzig,  1882. 

III. — ON  THE  POLLUTION  OF  STREAMS. 

Great  Britain  :  Rivers  Pollution  Commission,  appointed  in  1865.  Three 
Reports.  Parliamentary  Documents.  4to.  London,  1866-67. 

Great  Britain  :  Rivers  Pollution  Commission,  appointed  in  1868.  Six  Re- 
ports. Parliamentary  Documents.  4to.  London,  1870-74. 

Massachusetts :  Seventh  Annual  Report  of  the  State  Board  of  Health, 
containing  a  special  report  on  the  pollution  of  streams,  etc.  8vo.  Boston, 
1876. 

Paris :  Assainissement  de  la  Seine.  Epuration  et  Utilisation  des  Eaux 
d'£gout.  Documents  administratifs  ;  Enquete  ;  Annexes.  3  vols.  8vo,  with 
plates.  Paris,  1876. 

IV. — ON  FILTRATION,  GROUND  WATER,  WELLS,  ETC. 

Belgrand,  M. :  Les  Travaux  souterrains  de  Paris.  Etudes  prdiminaires. 
La  Seine.  Regime  de  la  Pluie,  des  Sources,  des  Eaux  courantes.  Applica- 
tions a  P  Agriculture.  8vo,  pp.  612,  with  atlas.  Paris,  Dunod,  1875.  [Espe- 
cially chap,  vii,  Des,  nappes  d'eau  souterrains,  and  chap,  xxvi,  Du  filtrage 
des  eaux,  etc.] 

Berlin  :  Vorarbeiten  zu  eir.er  zukiinftigen  Wasserversorgung  der  Stadt 
Berlin.  Ausgefiihrt  in  den  Jahren  1868  und  1869  von  L.  A.  Veitmeyer. 
8vo,  pp.  368,  with  atlas.  Berlin,  Reimer,  1871.  [Especially  pp.  109-130 — 
experiments  on  the  ground  water  in  the  neighborhood  of  the  Tegeler  See.] 

Berlin  :  Reinigung  und  Entwasserung  Berlins.  Berichte  iiber  mehrere 
auf  Veranlassung  des  Magistrals  der  konigl.  Haupt-und  Residenzstadt  Berlin 
Versuche  und  Untersuchungen.  12  Hefte,  with  3  Anhange.  8vo.  Berlin, 


2l8  WATER   SUPPLY. 

Hirschwald,  1870-76.  [Especially  Heft  v,  "  iiber  die  Grundwasserverhalt- 
nisse,"  with  a  great  number  of  profiles.] 

Brooklyn,  N.  Y.  :  The  Brooklyn  Water  Works  and  Sewers.  Prepared 
and  printed  by  order  of  the  Board  of  Water  Commissioners.  4to,  pp.  159, 
with  59  lith.  plates.  New  York,  Van  Nostrand,  1867. 

Darcy,  Henry  :  Les  fontaines  publiques  de  la  ville  de  Dijon.  4to,  pp.  647, 
with  atlas.  [Especially  Appendix  D,  Filtrage.] 

Dresden  :  Das  Wasserwerk  der  Stadt  Dresden  erbaut  in  den  Jahren  1871- 
1874,  von  B.  Salbach.  8vo.  In  three  parts,  with  atlases  containing  many 
plates.  Halle,  Knapp,  1874-76. 

Dupasquier,  A.  :  Des  Eaux  de  Source  et  des  Eaux  de  Riviere  compare'es, 
etc.  I2mo,  pp.  414.  Paris  et  Lyon,  1840. 

Dupuit,  J.  :  Traite*  de  la  Conduite  et  de  la  Distribution  des  Eaux,  etc. 
Suivi  de  la  Description  des  Filtres  naturell.es  de  Toulouse  par  D'Aubisson. 
4to,  with  atlas.  Paris,  1854. 

Fischer,  Dr.  F.  :  Das  Trinkwasser,  seine  Beschaffenheit,  Untersuchung 
und  Reinigung  unter  Beriicksichtigung  der  Brunnehwasser  Hannover.  8vo, 
pp.  63.  Hannover,  1873. 

Gottisheim :  Das  unterirdische  Basel.  8vo,  pp.  72.  Basel,  1868.  [2d 
Edition,  1873.] 

Grahn  and  Meyer  :  Reisebericht  einer  von  Hamburg  nach  Paris  und  Lon- 
don ausgesandten  Commission  iiber  kiinstliche  centrale  Sandfiltration  zur 
Wasserversorgung  von  Stadten,  und  iiber  Filtration  in  kleinen  Massstabe. 
Von  E.  Grahn  und  F.  Andreas  Meyer.  8vo,  pp.  153.  Hamburg,  Meissner, 
1877.  [Especially  Anlage  3,  "Historische  Notizen  iiber  kiinstliche  Filtration 
im  kleineren  Massstabe."] 

Grimaud,  de  C  ux  :  Des  Eaux  publiques,  etc.  8vo,  pp.  348.  Paris,  Dezo- 
bry,  1863.  [Especially  chap,  xiv,  "  de  la  clarification  des  eaux  publiques."] 

Halle:  Das  Wasserwerk  der  Stadt  Halle,  erbaut  in  den  Jahren  1867  und 
1868.  Von  B.  Salbach.  Folio,  with  atlas.  Halle,  Knapp,  1871. 

Kirkwood,  J.  P.  :  Report  on  the  Filtration  of  River  Waters  for  the  Supply 
of  Cities,  as  practised  in  Europe.  410,  pp.  178,  with  30  plates.  New  York, 
Van  Nostrand,  1869. 

Munich  :  Berichte  iiber  die  Verhandlungen  und  die  Arbeiten  der  Commis- 
sion fiir  Wasserversorgung,  Canalisation,  und  Abfuhr.  Erster  Bericht,  1874- 
75  ;  Zweiter  Bericht,  1876,  und  Anhange,  1877.  4to,  with  plans  and  profiles. 
Munchen,  Muhlthaler,  1876,  1877. 

Nichols,  W.  R.  :  On  the  Filtration  of  Potable  Water.  Reprinted  from  the 
Ninth  Annual  Report  of  the  Mass.  State  Board  of  Health.  8vo,  pp.  93.  New 
York,  Van  Nostrand,  1879 

Pielke  :  Mittheilungen  iiber  natiirliche  und  kiinstliche  Sandfiltration,  nach 
Betriebsresultaten  der  Berliner  Wasserwerke  vor  dem  Stralauer  Thor.  8vo, 
pp.  75.  Berlin,  1881. 

Schorer,  Th. :  Liibeck's  Trinkwasser,  8vo,  pp.  284.  Liibeck,  Seelig,  1877. 
[Especially  pp.  248-257,  describing  the  deterioration  of  water  by  vegetable 
growth  and  decay,  etc.] 


BIBLIOGRAPHY.  2IQ 

Spon,  Ernest :  The  present  Practice  of  Sinking  and  Boring  Wells.  I2mo, 
pp.  216.  London,  Spon,  1875. 

Ward,  F.  O.  :  Moyens  cle  cre"er  des  sources  artificielles  d'eau  pure  pour 
Bruxelles.  8vo,  pp.  106.  Bruxelles,  Decq,  1853. 

Wiebel,  Dr.  F,  ;  Die  Fluss-  und  Bodenwasser  Hamburgs.  Chemische 
Beitrage  zur  Analyse  gewohnlicher  Lauf-  Nutz-  und  Trinkwasser  sowie  zu 
der  Frage  der  Wasserversorgung  grosser  Stadte  von  sanitaren  und  gewerb- 
lichem  Standpunkte.  4to,  pp.  152.  Hamburg,  Meissner,  1876. 

Wolff;  Der  Untergrund  und  das  Trinkwasser  der  Stadte.  2te  Auflage. 
8vo,  pp.  60.  Erfurt,  1873. 

V. — ON  THE  SANITARY  EXAMINATION  OF  WATER. 

Eyferth,  B.  :  Die  mikroscopischen  Siisswasserbewohner  in  gedrangter 
Uebersicht.  8vo,  pp.  60.  Braunschweig,  1877. 

Fox,  Cornelius  B.,  M.D. :  Sanitary  Examination  of  Water,  Air  and  Food. 
8vo,  pp.  508.  London,  1878. 

Frankland,  Dr.  E.  :  Water  Analysis  for  Sanitary  Purposes.  I2mo,  pp.  139. 
London,  Van  Voorst,  1880. 

Hassall  :  Microscopical  Examination  of  Water  Supplied  to  the  Inhabitants 
of  London,  etc.  London,  1851. 

Kubel,  Dr.  Wilhelm:  Anleitung  zur  Untersuchung  von  Wasser,  u.  s.  w. 
8vo,  pp.  184.  Zweite  Auflage  von  Dr.  Ferd.  Tiemann.  Braunschweig,  1874. 

Macdonald,  J.  D.,  M.D. :  A  Guide  to  the  Microscopical  Examination  of 
Drinking  Water.  8vo,  pp.  65  and  24  plates.  London  and  Philadelphia,  1875. 

Neuville :  Des  Eaux  de  Paris.  Essai  d'Analyse  micrographique  compared. 
4to,  pp.  63.  15  plates.  Paris,  1880. 

Schiitzenberger:  On  Fermentations.  I2mo,  pp.  331.  Intern.  Sci.  Series. 
New  York,  1876.  [This  contains  a  description  of  Schiitzenberger's  method  of 
determining  dissolved  oxygen,  pp.  108  and  foil.] 

Wanklyn,  J.  A. :  Water  Analysis:  a  Practical  Treatise  on  the  Examination 
of  Potable  Water.  By  J.  A.  W.  and  E.  T.  Chapman.  I2mo,  pp.  182.  Fifth 
edition,  re-written  by  J.  A.  Wanklyn.  London,  1879. 

VI. — MISCELLANEOUS. 

Boston,  Mass.;  Report  of Cochituate  Water  Board,  1874.  [Contains  are- 
print  of  a  report  by  Geo.  F.  Deacon,  Borough  Engineer,  Liverpool,  Eng.,  on 
the  subject  of  "  Waste."] 

Boston,  Mass.:  Report  on  Waste  of  Water  (May  25,  1882).  Boston  City 
Document  No.  78,  1882. 

Bowditch:  Public  Hygiene  in  America.    8vo.     Boston,  1877. 

Deacon  :  The  Constant  Supply  and  Waste  of  Water.  A  paper  read  before 
the  Society  of  Arts,  May  19,  1882.  4to,  London,  1882. 

Magnin:  The  Bacteria,  translated  by  Dr.  Geo.  H.  Sternberg,  U.  S.  A. 
8vo,  pp.  227.  Boston,  1880. 

Nageli:  Die  niederen  Pilze.     Munchen,  1877. 


220  WATER  SUPPLY. 

Nageli:  Untersuchungen  iiber  niedere  Pilze.  8vo,  pp.  285.  Munchen 
und  Leipzig,  1882.  [This  contains  Buchner's  paper  referred  to  on  page  21.] 

De  Ranee :  The  Water  Supply  of  England  and  Wales.  8vo,  pp.  623.  Lon- 
don, 1882. 

Kuessner  und  Pott:  Die  acuten  Infectionskrankheiten.  8vo,  pp.  460. 
Braunschweig,  1882. 

Parry:  Water,  its  Composition,  Collection,  and  Distribution.  I2mo,  pp. 
184.  London,  1881. 

Rowan:  Boiler  Incrustation  and  Corrosion.  i8mo,  pp.  48.  New  York, 
Van  Nostrand,  1876. 

Wilson:  Treatise  on  Steam  Boilers.  Third  edition.  I2mo,  pp.328.  Lon- 
don, 1875. 


TABLES   FOR  CALCULATION. 


221 


TABLE  XXXI. — For  the  Conversion  of  Degrees  of  Fahrenheit's  Scale  into  those  of 
the  Centigrade  Thermometer. 


FAHR. 

CENT. 

FAHR. 

CENT. 

FAHR. 

•  CENT. 

FAHR. 

CENT. 

0 

—  17.7 

54 

12.2 

107 

41.6 

1  60 

71.  1 

I 

-  iy.2 

55 

13-7 

1  08 

42.2 

161 

71.6 

2 

-  16.6 

56 

13  3 

log 

42.7 

162 

72.2 

3 

-  16.1 

57 

I3.8 

no 

43-3 

163 

72.7 

4 

-  15-5 

58 

14.4 

III 

43.8 

164 

73-3 

5 

-  15 

59 

15 

112 

44.4 

165 

73-8 

6 

—  14.4 

60 

15  5 

113 

45 

1  66 

74-4 

7 

-  13-8 

6t 

16.1 

114 

45-5 

167 

75 

8 

-  13-3 

62 

16.6 

H5 

46.1 

168 

75-5 

9 

—  12.7 

63 

17.2 

u6 

46.6 

169 

76.1 

10 

—  12.2 

64 

17.7 

117 

47.2 

170 

76.6 

ii 

-  II.  6 

65 

18.3 

118 

47-7 

171 

77.2 

12 

—  II.  I 

65 

18.8 

119 

48.3 

1/2 

77-7 

13 

-  10.5 

67 

19.4 

120 

48.8 

173 

78.3 

14 

—  IO 

68 

20 

121 

49-4 

174 

78.8 

15 

-  .  9.4 

69 

2O.5 

122 

50 

175 

79-4 

16 

-  8.8 

70 

21.  1 

123 

50.5 

I76 

80 

17 

-  8.3 

71 

21.6 

124 

51-  1 

177 

80.5 

18 

-  7-7 

72 

22.2 

125 

51-6 

I78 

81.1 

J9 

-  7-2 

73 

22.7 

126 

52.2 

I79 

81.6 

20 

-  6.6 

74 

23-3 

127 

52-7 

1  80 

82.2 

21 

-  6.1 

75 

23-8 

128 

53-3 

181 

82.7 

22 

-  5-5 

76 

24.4 

129 

53-8 

182 

83.3 

23 

-  5 

77 

25 

130 

54-4 

183 

83.8 

24 

—  4.4 

78 

25-5 

131 

55 

184 

84.4 

25 

-  3-8 

79 

26.1 

132 

55-5 

185 

85 

26 

-  3-3 

80 

26.6 

133 

56.1 

1  86 

85.5 

27 

-  2.7 

81 

27-2 

134 

56.6 

187 

86.1 

28 

82 

27.7 

135 

57-2 

188 

86.6 

29 

-  i!6 

83 

28.3 

136 

57-7 

189 

87.2 

30 

—  i.i 

84 

28.8 

137 

58.3 

190 

87.7 

31 

-  0.5 

85 

29.4 

138 

58.8 

191 

88.3 

32 

o 

86 

30 

139 

59-4 

192 

88.8 

33 

0.5 

87 

3°-5 

140 

60 

193 

89.4 

34 

ii 

88 

3i-i 

141 

60.5 

194 

90 

35 

1.6 

89 

31-6 

142 

61.1 

195 

90-5 

36 

2.2 

90 

32  2 

143 

61.6 

196 

91.1 

37 

2.7 

9i 

32-7 

144 

62.2 

197 

91.6 

33 

3-3 

92 

33-3 

145 

62.7 

198 

92.2 

39 

3-8 

93 

33-8 

146 

63-3 

199 

92.7 

40 

44 

94 

34-4 

147 

63.8 

200 

93-3 

4i 

5 

95 

35 

148 

64.4 

20  1 

93-8 

42 

5-5 

96 

35-5 

149 

65 

202 

94.4. 

43 

6  i 

97 

36.1 

150 

65.5 

2O3 

95 

44 

6.6 

98 

36.6 

151 

66.1 

2O4 

95-5 

45 

7.2 

99 

37-2 

152 

66.6 

205 

96.1 

46 

7-7 

IOO 

37-7 

153 

67.2 

206 

96.6 

47 

8-3 

101 

38.3 

154 

67.7 

2O7 

97.2 

48 

8.8 

102 

38.8 

155 

68.3 

208 

97-7 

49 

9.4 

103 

39-4 

156 

68.8 

209 

98-3 

50 

10 

104 

40 

157 

69.4 

2IO 

98.8 

5i 

10.5 

105 

40  5 

158 

70 

2TI 

99-4 

52 

ii.  i 

106 

41.1 

159 

70.5 

212 

IOO.O 

53 

ii.  6 

222 


WATER   SUPPLY. 


TABLE    XXXII. — For  the  Conversion  of  Degrees  of  the  Centigrade  Thermometer  into 
Degrees  of  Fahrenheit's  Scale \ 


CENT. 

FAHR. 

CENT. 

FAHR. 

CEXT. 

FAHR. 

CENT. 

FAHR. 

O 

32.0 

26 

78-8 

51 

123.8 

76 

168.8 

I 

33.8 

27 

80.6 

52 

125.6 

77 

170.6 

2 

35-6 

28 

82.4 

53 

127.4 

78 

172.4 

3 

37-4 

29 

84.2 

54 

129.2 

79 

174.2 

4 

39-2 

30 

86.0 

55 

I31.O 

80 

176.0 

5 

41.0 

31 

87.8 

56 

132.8 

81 

177-8 

6 

42.8 

32 

89.6 

57 

134.6 

82 

179.6 

7 

44.6 

33 

91.4 

58 

136.4 

83 

181.4 

8 

46.4 

34 

93-2 

59 

138.2 

84 

183.2 

9 

48.2 

35 

95-o 

60 

140.0 

85 

185.0 

10 

50.0 

36 

96.8 

61 

I4I.8 

86 

186.8 

ii 

51-8 

37 

98.6 

62 

143.6 

87 

1  88.  6 

12 

53-6 

38 

100.4 

63 

145-4 

88 

190.4 

13 

55-4 

39 

IO2.2 

64 

147.2 

89 

192.2 

14 

57-2 

40 

IO4.O 

65 

149.0 

90 

194.0 

15 

59-o 

41 

105.8 

66 

150.8 

9i 

195.8 

16 

608 

42 

107.6 

67 

152.6 

92 

197.6 

17 

62.6 

43 

109.4 

68 

!54-4 

93 

199.4 

18 

64-4 

44 

III.  2 

69 

156.2 

94 

2OI.2 

19 

66.2 

45 

II3.0 

70 

158.0 

95 

203  o 

20 

68.0 

46 

IT4.8 

7i 

159.8 

96 

204.8 

21 

69.8 

47 

116.6 

72 

161.6 

97 

206.6 

22 

71.6 

48 

118.4 

73 

163.4 

98 

208.4 

23 

73-4 

49 

I2O.2 

74 

165.2 

99 

2IO.2 

24 

75-2 

50 

122.0 

75 

167.0 

100 

212.0 

25 

77.0 

METRIC  SYSTEM  OF  WEIGHTS  AND  MEASURES. 
Weights. 


I  Milligram     mgm. 

I  Centigram 

I  Decigram 

I  Gram  grm. 


=  o.ooi  gram. 

=  O.CI  " 

=   0.1  " 

=   1.0 


I  Gram  grm.      =         i  gram. 

I  Dekagram  =      10  grams, 

i  Hectogram  =     100       " 

I  Kilogram  kilo.      =  1000       " 


Measures  of  Length, 


I  Millimeter    m.m. 
I  Centimeter     c.m. 
I  Decimeter      d.m. 
i  Meter                m. 

=  o.ooi    meter. 

=  O.OI              " 
=   I.O                " 

I  Meter 
i  Dekameter 
I  Hectometer 
I  Kilometer  kilom. 

=         I  meter. 
=       10  meters. 

=      100        " 
=   IOOO        " 

Measures  of  Volume. 


I  Cubic  Centimeter 
I  Cubic  Decimeter 
I  Cubic  Meter 


c.c.  or   c.m.       =        o.ooi  liter, 
dm.       =         i.ooo     " 
m.      =  looo.ooo    4* 


WEIGHTS  AND   MEASURES. 


223 


s 

I 

oo        eno        O"1 

i! 

OO          ^  O^  t^«vO 
en       O  r^  en  en 
en       N  en  r^  o 

oo   O   N   <N   rj-  O 
»..,«} 

8 
| 

T|-  i^»      O 
r->.  c^i        O 

NO        O 

M  r^«  M  co  r^  M 

y 

5 

N  M        r^  O 

3 

u 

0 

i 

a  it 

in  en        in 

y 

CO     TT           -1 

u 

l^>«  m        en 

en  ^  1-1  co 

o 

8888 

X 

3 

O   O  O  O   M 

H 
"S. 

3 

I 

co   m  M         O 

5 

£ 

.H 
2 

vO   *T  ^^       *O 
co  Q   w>       \O 

J?^  £       en 

jj 

U 

O   O   O   M  in 

en  r^       O 
O  m      oo 

in  en        in 

e 

CO    rf         M 

r^.  m       en 

•- 

en  ^  M  co  O 

CM    O 

Imperial  Gallons. 

en        O   N  --O    1 
en       W   en  O 

CO           N    M    O 

o'  M  6  o  o 

vC    N 

i 

ex  co   in  r». 

en  HI   M   in 

15 
O 

O  *O  co  co 

N    (N    Tf-  M 

C/3 

""°^ 

M 



M 

:  §      :  :  : 

h 
o 

J2  bfl     "o  "5  'o 

u 

^  *TJ         r      ^    ^ 

s 

tx.5      ^      ^^ 

•    ^    u    0    0    0 

^    D-  0)  ^  U2  ^D 

•    g  .ti    3    3    3 

S  g  i  -8  | 

ii  ll 


:|  jf  1 1  «  2  ^ 

«  o  |  £  i  |  £ 

•u  ^  «4_  £  3  en 

*o  £  S  O  c/2  n-i  rt 


tlllJll 

I.  Jl  i  t.  P  W  I 

u     _,    n3  >,  -" 


1^ 

si 


a  .5"  o 

S  S3 

*-  (U     3 

C    b    <u  'O    ° 


g 

K>  'S  ^j 

-a  S  1 


.3  * 

-8 


•<*-'o  M-L 

J*  3^. 


f  S  "S  8    § 


!J~" 

w 

E- 

IQ 

— 

-- 

__    . 

^ 

-- 

-- 

rri 

W 

—       . 

M 

U 

— 

-- 

M 

-- 

— 

- 

i- 

- 

=- 

224 


WATER  SUPPLY. 


TABLE  XXXIV.—  For  Facilitating  Approximate  Calculations  from  one 
Denomination  into  another. 


FEET. 

METERS. 

POUNDS 
AVOIRDU- 
POIS. 

KILO- 
GRAMS. 

U.S. 
GALLONS. 

IMPERIAL 
GALLONS. 

LITERS. 

CUBIC 
METERS. 

I 

0.30 

I 

0.45 

I 

0.83 

3-79 

0.0038 

2 

0.61 

2 

0.91 

2 

1.67 

7-57 

0.0076 

3 

0.91 

3 

1.36 

3 

2.50 

11.36 

0.0114 

4 

1.22 

4 

1.81 

4 

3.33 

15.14 

O.OI5I 

5 

1-52 

5 

2.26 

5 

4.17 

18.93 

0.0189 

6 

1.83 

6 

2.72 

6 

5.00 

22.71 

0.0227 

7 

2.13 

7 

3.18 

7 

5-83 

26.50 

0.0265 

8 

2-44 

8 

3.62 

8 

6.66 

30.38 

0.0303 

9 

2.74 

9 

4.08 

9 

7.50 

34-07 

0.0341 

3-28 

I 

2.20 

I 

1.  20 

I 

4-54 

0.0045 

6.56 

2 

4.41 

2 

2.40 

2 

9  08 

0.0091 

9.84 

3 

6.61 

3 

3-60 

3 

13-63 

0.0136 

13-12 

4 

8.82 

4 

4.80 

4 

18.17 

O.OI82 

16.40 

•5 

11.02 

5 

6.00 

5 

22.71 

0.0227 

19.69 

6 

I3.23 

6 

7.20 

6 

27.26 

0.0273 

22.97 

7 

15-43 

7 

8.40 

7 

31.80 

0.0318 

26.25 

8 

17.64 

8 

9.60 

8 

36.34 

0.0363 

29.53 

9 

19.84 

9 

10.80 

9 

40.89 

0.0409 

MILES. 

KILO- 
METERS. 

KILO- 
METERS. 

MILES. 

I 

I.6l 

I 

0.62 

0.26 

0.22 

i 

0.001 

2 

3-22 

2 

1.24 

0-53 

0.44 

2 

O.OO2 

3 

4.83 

3 

1.86 

0.79 

0.66 

3 

0.003 

4 

6.44 

4 

2.49 

1.05 

0.88 

4 

O.OO4 

5 

8.05 

5 

3-II 

1.32 

.10 

5 

0.005 

6 

9.66 

6 

3-73 

1.58 

•  32 

6 

0.006 

7 

11.27 

7 

4-35 

1.85 

•54 

7 

O.OO7 

8 

12.87 

8 

4-97 

2.  II 

.76 

8 

0.008 

9 

14-48 

9 

5-59 

2.38 

.98 

9 

0.009 

TABLES   FOR   CALCULATION. 


225 


TABLE  XXXV. — For  the  Conversion  of  Parts  per  100,000  into  Grains  per  Gallon, 
and  vice  versa  :  also,  for  Comparing  Degrees  of  Hardness. 


PARTS  IN  100,000. 

GRAINS  IN 
U.   S.   STANDARD 
GALLON. 

GRAINS  IN 
IMPERIAL 
GALLON. 

DEGF 

French  : 
Parts  CaCO3 
in  ico,ooo. 

EES  OF  HARD 

English  : 
Grains 
CaCO3  in 
imp.  Gallon. 

NESS. 

German  : 
Parts  CaO 
in  ico,ooo. 

I 

0.5837 

0.7 

I 

0.7 

0.6 

2 

1.1674 

1.4 

2 

1.4 

i.i 

3 

I.75I2 

2.  1 

3 

2.1 

1-7 

4 

2-3349 

2.9 

4 

2.8 

2.2 

5 

2.9186 

3-5 

5 

3-5 

2.8 

6 

3-5023 

4.2 

6 

4-2 

3-4 

7 

4.0861 

4-9 

7 

4-9 

3-9 

8 

4.6698 

5-6 

8 

5-6 

4-5 

9 

5-2535 

6-3 

9 

6-3 

5-0 

1.7131 

I 

1.1992 

1-4 

i 

0.8 

3.4262 

2 

2-3983 

2.9 

2 

1.6 

5-1393 

3 

3-5975 

4-3 

3 

2.4 

6.8524 

4 

4.7967 

6-7 

4 

3-2 

8.5655 

5 

5-9958 

7-1 

5 

4.0 

10.2786 

6 

7-I950 

8.6 

6 

4-8 

11.9917 

7 

8.3942 

IO.O 

7 

5-6 

13.7048 

8 

9-5934 

ii.  4 

8 

6.4 

I5-4I79 

9 

10.7925 

12.8 

9 

7-2 

1.4286 

0.8339 

i 

1.8 

1.2 

i 

2.8571 

1.6678 

2 

3-6 

2-5 

2 

4-2857 

2.5017 

3 

5-4 

3-8 

3 

5  7143 

3-3356 

4 

7-1 

5  o 

4 

7.1428 

4-1695 

5 

9.0 

6-3 

5 

8.5714 

5  0033 

6 

10.7 

7-5 

6 

IO.OOOO 

5-83/2 

7 

12.6 

8.8 

7 

11.4286 

6.6711 

8 

14-3 

IO.O 

8 

12.8571 

7-5050 

9 

16.1 

II-  3 

9      II 

15 


INDEX. 


ABERDEEN,  corrosion  of  pipes  in,  208. 

Absorption  of  gases,  n. 

Aeration,  150. 

Africa,  artesian  wells  in,  134. 

Air,  composition  of,  12. 

Aire  and  Calder  rivers,  pollution  of,  58. 

Alabama,  artesian  wells  in,  135. 

Albuminoid  ammonia,  39. 

Alga?  at  Berlin,  157. 

in  deep-seated  water,  143. 
in  water  supplies,  86. 
spores  not  removed  by  sand  filtra- 
tion, 165. 

Algeria,  artesian  wells  in,  135. 
Altenburg,  consumption  of  water  in,  194. 

water  supply  of,  207. 
Alton,  111.,  filters  at,  168. 
Altona,  consumption  of  water  in,  194. 
filtration  at,  156. 
use  of  Barff's  process  in,  209. 
Alum,  treatment  of  water  with,  187. 
Ammonia,  coefficient  of  absorption  of,  II. 

determination  of,  37. 
Ammonia  method  of  water  analysis,  37, 

38- 

Amsterdam,  water  supply,  121. 
Anabcena  circinalis,  87,  88. 
Analyses,  methods  of  reporting,  8,  30. 
Analysis,  methods  of,  29. 
Animal  life,  79. 
Anthrax,  20. 

Aquamalarial  fever,  52,  100. 
Artesian  wells  at  Crenelle,  Paris,  137. 
St.  Louis,  137. 
Charleston,  S.  C.,  135. 
in  Alabama,  135. 
Algeria,  134. 
China,  134. 
examination    of    (Table), 

144. 

pollution  of,  143. 
uncertainty  of,  137. 
Artificial  ice,  53. 
Atkins's  cistern  filters,  178. 

BACILLUS,  -LI,  20. 

anthracis,  20. 

subtilis,  21. 
Bacteria,  19,  45,  67. 

removed  by  spongy  iron,  173. 


Baird's  system  of  distillation,  190. 
Baltimore,  Md.,  water  supply,  204. 
Bamberg,  consumption  of  water  in,  194. 
Bangor,  Me.,  filters  at,  169. 
Barff's  process,  209,  215. 
Belgium,  pollution  of  streams  in,  72. 
Belgrand,  quoted,  120. 
Bell's  waste  detector.  201. 
Berlin,  experience  with  meters,  204. 
filtration  at,  157. 

ground  water  measurement  at,  no, 
water  supply,  trouble  in,  125. 
Bibliography,  216. 
Biological  examination  of  water,  45. 
Birmingham,    consumption   of   water   in, 

194. 
Bischof's  experiments  on  bacteria,  173. 

spongy  iron  for  filters,  166,  327. 
Blackburn,   Eng.,  consumption  of   water 

in,  194. 

Blackstone  River,  pollution  of,  59,  62. 
Bohemia,  spring  and  well  waters  in,  145. 
Boiler  scale,  181. 

Bone  coal  for  filters,  170,  334,  336. 
Bonn,  consumption  of  water  in,  194. 
Boston,  consumption  of  water  in,  195. 
corrosion  of  iron  pipes  in,  209. 
lead  pipes  in,  213. 
waste  water  inspection,  201. 
water,  examination  of,  101,  104. 
Bower-Barff  process.      See  Barff. 
Brackett,   Dexter,  quoted,   194,  195,  200, 

201,  205. 

Bradford  Beck,  pollution  of,  58. 
Braunschweig,  consumption  of  water  in, 

194. 

Breslau,  experience  with  meters,  204. 
Brewer,  Dr.,  quoted,  52. 
Brick  for  filters,  168,  332. 
Brooklyn,  daily  consumption  in,  195. 

inspection  of  plumbers'  fittings, 

205. 

water  supply  of,  105. 
well  in  Prospect  Park,  in. 
Buchanan,  quoted,  15. 
Buchner's    experiments    on   Bacillus    an- 
thracis, 21. 

CAMBRIDGE,  Mass.,  consumption  of  water 
in,   195. 


228 


INDEX. 


Carbide  of  iron  for  filters,  166. 
Carbonate  of  lime,  solubility  of,  9. 
Carbonic   acid,  coefficient    of  absorption, 

ii. 

solution  of,  12. 
in  natural  waters.  31. 
Cast-iron  pipes,  corrosion  of,  207. 

method  of  coupling,  209. 
Cellulose  used  for  filters,  180. 
Chandler,  analysis  of  Croton  water,  8. 
Charbon,  20. 

Charleston,  S.  C,  artesian  wells  at,  135. 
Chemical  analysis,  value  of,  44. 
solution,  2. 

treatment  of  water,  187. 
with  alum,  187. 
with  lime,  183,  188. 
with  perchloride  of  iron,  187. 
with   permanganate    of  pot- 
ash, 188. 
Chicago,  consumption  of  water  in,  195. 

River,  pollution  of,  59. 
China,  artesian  wells  in,  134. 
Chlorides,  significance  of,  33,  68. 
Chlorine,  a   means    of   tracing  pollution, 

I3X. 

in  natural  waters,  33. 
estimation  of,  33. 
Cholera  and  drinking  water,  22. 
Church's  waste  indicator,  379. 
Cincinnati,  consumption  of  water  in,  195. 

detection  of  waste,  201 . 
Cistern  filters,  176. 

water,  examination  of,  50. 

(Table),  5 1. 

Cisterns,  sediment  in,  50. 
Clark's  process,  183. 
Classification  of  waters,  17,  42,  43. 
Clathrocystis  aeruginosa,  88. 
Clinton,  Iowa,  filters  at,  168. 
Clyde,  pollution  of,  59. 
Coelosphserium,  87. 
Cologne  (Coin),  consumption  of  water  in, 

194. 

Color,  method  for  estimating,  149. 
Conduits,  206. 

growth  of  sponge  in,  207. 
various,  length  of,  207. 
Consumption  of  water  in  American  cities, 

195. 
European  cities, 

194. 
Corroded  pipes,  diminished  flow  through, 

207. 

Corrosion  of  cast-iron  pipes,  207. 
Couste,  quoted,  5. 
Crenothrix  Kuhniana,  126,  210. 
Crookes,  Prof.,  quoted,  188. 
Croton  water,  action  on  lead,  213. 

analysis  of,  8. 
Cucumber  taste,  91. 
Cyclops  quadricornis,  70. 


DANUBE,  suspended  matter  in,  57. 
Danzig,  water  supply  of,  207. 
Daphnia  pulex,  79. 

Davis,  J.  P.,  cost  of  sand  filtration,  165. 
Deacon's  system  in  Liverpool,  199. 

Glasgow,  200. 

Boston,  201. 

Deacon's  waste  water  meter,  196-199. 
Deep-seated  water,  algae  in,  143. 

as  a  source  of  supply, 

133-145. 

characteristics  of,  142. 
examination  of ,  142. 
(Tables),  144,  145. 
pollution  of,  143. 
Deep  sea  thermometer,  95. 
Deep  wells,  134,  139. 

examination  of  (Table),  144. 
Degrees  of  hardness,  34. 

different    thermometers    com- 
pared, 221,  222. 
Deposition  as  means  of  self-purification, 

67. 

De  Ranee,  quoted,  137,  141. 
Desmids,  86. 
Detroit,  consumption  of  water  in,  195. 

wooden  pipes  in,  211. 
Diatoms,  86. 
Dilution  as  means  of  natural  purification, 

68. 

a  guaranty  of  safety,  71. 
Discharge  from  corroded  pipes,  208. 
Disease  and  drinking  water,  17-28. 
Dissolved  solids,  effect  of,  10. 

estimation  of,  32. 
Distillation,  189. 

Baird's  system,  190. 
Normandy's  system,  192. 
Distribution  pipes,  206. 
Double  supply,  206. 
Dresden,  consumption  of  water  in,  194. 

ground  water  measurements,  no. 
water  supply  of,  108,  120. 
Drinking  water  and  disease,  17-28. 
best,  133. 
theory,  22. 
Drinking,  water  most  suitable  for,  27. 
Driven  wells,  109,  112-117. 

principle  of,  114. 
Dublin,  consumption  of  water  in,  194. 
Dubuque,  Iowa,  water  supply  of,  138. 
Durance,  suspended  matter  in,  57. 

EDINBURGH,  consumption  of  water  in,  194. 
Elbe  filtered  at  Altona,  156. 

pollution  of,  71. 
Emmerich,  Dr.,  quoted,  24,  26,  45. 
England,  pollution  of  streams  in,  73, 

FALL  RIVER,  Mass.,  consumption  of  water 

in,  195. 
use  of  meters  in,  203. 


INDEX. 


229 


Ferrous  sulphate  test,  35. 
Filter,  Piefke's,  180. 

the  multifold,  179. 
Filter  basin  at  Waltham,  Mass.,  119. 
Filter  beds,  advantage  of  covering,  163. 
construction  of,  151,  155. 
frequency  of  cleaning,  157. 
method  of  cleaning,  152. 
Filter  gallery  at  Columbus,  O.,  108. 
Halle,  108. 
Lowell,  107. 
Taunton,  108. 

Filters,  household,  bone  coal  for,  170,  172. 
for  cisterns,  176-178. 
requirements  of,  170. 
reversible,  171. 
silicated  carbon  for,  172. 
simple  form  of,  174. 
spongy  iron  for,  173. 
wood  charcoal  for,  1 74. 
Filter  press,  Porter's,  185. 
Filtration,  151. 

at  Alton,  111.,  168. 
Altona,  156. 
Antwerp,   166. 
Bangor,  Me.,  169. 
Berlin,  157,  158,  160,  164. 
Clinton,  Iowa,  168. 
Hudson,  N.  Y.,  161,  163. 
London,  159,  160. 
Magdeburg,  164. 
Malone,  N.  Y.,  168. 
Marshalltown,  Iowa,  168. 
Poughkeepsie,  N.  Y  ,  162. 
Wakefield,  Eng.,  166. 
Zurich,  157. 
extent  of,  151. 
expense  of,  165. 
for  manufactories,  179. 
household,  169. 

materials  used,  169. 
in  winter,  164. 
natural,  106,  117. 
principles  of,  152. 
rate  of,  152,  156,  158. 
(See  also  Filters,  household.) 
Flint,  Dr.  Austin,  quoted,  23. 
Flushing,  water  supply  of,  193. 
Forel,  Dr.,  quoted,  80. 
Fox,  Dr.  C.  B.,  quoted,  44. 
France,  pollution  of  streams  in,  59,  73. 
Frankfort,  consumption  of  water  in,  194. 
temperature  of  water,  207. 
water  supply,  207. 
Frankland,  Dr.,  quoted,  35,  40,  41. 
Frankland's  classification  of  water,  41. 
method  of  analysis,  37,  39. 
report  on  Antwerp  niters,  166. 

GALVANIZED  IRON,  corrosion  of,  214. 
Ganges,  suspended  matter  in,  57. 
Gases,  coefficient  of  absorption,  n. 


Gases  in  natural  waters,  31. 
solution  of,   io. 

supersaturated  solutions  of,  12. 
Germ  theory,  18. 

Germany,  pollution  of  streams  in,  59. 
Glasgow,  consumption  of  water  in,  .94. 

inspection  of  fittings  in,  205. 

lead  pipe  in,  213. 

water  supply  of,  207. 

waste  water  detection,  200. 
Glasgow  water,  examination  of,  101. 
Gold,  solubility  of,  15. 
Gotha,  water  supply  of,  207. 
Grahn,  quoted,  151. 
Great  Britain,  pollution  of  streams  in,  58, 

73- 

I  Greaves,  Mr.  Chas.,  on  filter  sand,  155. 
Grenelle,  Paris,  artesian  well  at,  137. 
Ground  water  as  source  of  supply,  105, 

132. 

defined,  105. 
effect  of  pumping  on,  109- 

112. 

examination  of,  122. 

(Table),  124. 
hardness  of,  120. 
inclination  of,  105. 
temperature  of,  118. 
utilization  of,  106,  109. 
Ground-water  supplies,  difficulties  of,  123, 

128.      • 

at  Berlin,  125-127. 
Halle,  127. 
Leipzig,  123. 
Lille,  127. 

HALLE,  water  supply  of,  108. 

trouble  with,  127. 

Hamburg,  consumption  of  water  in,  194. 
Hannover,  consumption  of  water  in,  194. 
Hardness,  degrees  of,  34. 

determination  of,  33. 

permanent,  33,  186. 

temporary,  34,  181. 
Hard  water,  17,  181. 

softening  of,  181-187. 
wholesomeness  of,  18. 
Hatton,  experiments  on  spongy  iron,  173. 
Head,  term  defined,  156. 
Heisch's  test,  46. 
Hoadley,  J.  C..  quoted,  116. 
Hooghly,  character  of  water,  16. 
Household  filtration  (See  Filtration). 
Hudson,  N.  Y.,  filtration  at,  161,  163. 
Hull,  Eng.,  consumption  of  water  at,  194, 
Humus,  84. 
Hunt,.  T.  Sterry,  quoted,  16. 

ICE,  chemical  examination  of,  54,  55. 
impure,  52. 
in  filtered  water,  179. 
natural  and  artificial,  52. 


230 


INDEX. 


Impounding  reservoirs,  85. 
Improvement  of  natural  water,  146. 
by  aeration,  150. 
chemical  processes,  187. 
Clark's  process,  181. 
distillation,  189. 
filtration,  151. 
sedimentation,  147. 
softening,  181. 
storage,  149. 
Infusoria,  83. 
Iron,  carbide  of,   166. 

compounds  of ,  in  ground  water,  123, 

125,  129. 

perchloride  of,  187. 
pipes,  corrosion  of,  207. 
protection  of,  208. 
sediment  in,  210. 
spongy,  1 66. 

Irrawaddy,  suspended  matter  in,  57. 
Irwell,  pollution  of,  58. 

JAMIESON,  M.  B.,  quoted,  207. 

KARLSRUHE,  consumption   of    water   in, 

194. 

Kassel,  consumption  of  water  in,  194. 
Kerner,  quoted,  207. 
Kirkwood,  quoted,  155,  164. 
Koch,  quoted,  20. 
Koch's  biological  method,  46. 

LATHAM,  quoted,  92,  141,  143. 

Latham's  apparatus  for  tempering  water, 

93- 

Lawrence,  Mass.,    manufacturing  indus- 
tries at,  63. 
Laws  against  pollution  of  water  supplies, 

71-78. 

Lead  pipes,  action  of  water  on,  211-214. 
Lead  poisoning,  213. 
Leeds,  Eng.,  consumption    of  water  in, 

194. 
Leipzig,  consumption  of  water  in,  194. 

water  supply  of,  123. 
Leyden,  water  supply  of,  121. 
Lille,  trouble  with  water  supply,  127. 
Lime,  water  treated  with,  183,  188. 
Liverpool,  Eng.,  consumption  of  water  in, 

194. 

inspection  of  fittings  in,  205 . 
softening  of  water  at,  1 85. 
water  supply,  138. 

London,  results  of  filtration  at,  159,  160. 
temperature  of    water  supplies, 

93- 

water,  examination  of,  102. 
water  supply,  102,  138. 
wells  in  and  near,  137. 
Long  Island,  N.  Y.,  ground  water  on,  105, 

III,   121. 

Loss  on  ignition,  37. 


Lowell,  Mass.,  consumption  of  water  in, 

195. 

filtering  gallery  at.  107. 
manufacturing   refuse  at, 
63- 

MAAS,  suspended  matter  in.  57. 
Magdeburg,  experience  with  meters,  204. 

filter  beds  at,  164. 
Manchester,  Eng.,  consumption  of  water 

in,  194. 
inspection    of    fittings 

in,  205. 

lead  pipe  in,  213. 

Mallet,  Prof.,  quoted,  24,  25,  35,  40,  42. 
Malone,  N.  Y.,  filters  at,  168. 
Marshalltown,  Iowa,  filters  at,  168. 
Memphis,  cisterns  in,  50. 
Merrimack  river,  pollution  of,  62,  63. 
Meters  for  checking  waste,  203. 

German  experience  with,  204. 
Microbes,  19. 
Micrococcus,  -ci,  20. 
Microzymes,  19. 
Milzbrand,  20. 
Mississippi  filtered  at  Alton,  168. 

sediment  in,  16,  57. 
Mixed  solutions,  condition  of,  7. 
Mountain  fever,  52,  100. 
Multifold  filter,  179. 
Munich,  water  supply  of,  207. 

NATURAL  filtration.  106,  117. 
Nageli,  quoted,  19. 
Nessler  test,  delicacy  of,  34. 
New  Orleans,  cisterns  in,  49. 

wells  in,  130. 

New  River  water,  filtered,  160. 
New  York,  inspection  of  fittings,  205. 
lead  pipes  in,  213. 
water  supply,  194,  207. 
wells  in,  138. 
Nitrites  and  nitrates,  35. 

significance  of,  36. 

Nitrogen,  coefficient  of  absorption,  n. 
(combined)  in  water,  34. 
in  natural  waters,  31. 
organic,  34. 
Nodularia,  89. 

Normandy's  system  of  distillation,  192. 
Nostocs,  87. 

ODORS  and  tastes  of  surf  ace  waters,  80,  84, 

85,  90. 

Ohio  River,  pollution  of,  70. 
Organic  and  volatile  matter,  37. 
Organic  c  rbon,  40. 

•   matter,  24,  36,  38. 

nitrogen,  34. 

Oxidation,  a  means  of  purification,  66. 
Oxygen,  coefficient  of  absorption,  II. 
in  natural  waters,  31. 


INDEX. 


231 


PARIS,  consumption  of  water  in,  194. 

water  supply  of,  207. 
Passaic  River,  pollution  of,  59,  17°- 
Pawtucket,  R.  I.,  use  of  meters  in,  203. 
Permanganate  method  of  analysis,  37. 

of     potash,     a     purifying 

agent,  iSS. 
in  analysis,  37. 
Philadelphia,   consun  p.ion    of   water   in, 

195. 

Physical  solution,  i. 
Picfkc,  quoted,  157,  161. 
Piefke's  filter,  180. 
Pipes,  brass,  214. 

enamelel,  214. 
galvanized  iron,  214. 
iron  (Ste  Iron  pipes), 
lead,  2ir. 
service,  211. 
tin-lined  lead,  214. 
wooden,  211. 
wrought  iron,  210. 
Plants,  aquatic,  83. 
Polluting  liquids  denned,  74. 
Pollution  of  streams,  57,  78. 

prevention  of,  71-78. 
of  wjlls,  128. 
Popular  tests,  46. 
Porter-Clark  process,  184. 
Po,  suspended  matter  in,  57. 
Poramogeton,  83. 
Potash,  permanganate  of,  37,  iSS. 
Poughkeepsie,  alga;  at,  90. 

filtration  at,  161,  162. 
Previous  sewage  contamination,  35. 
Protection  of  iron  pipes,  208. 
Providence,  consumption  of  water  in,  195. 
inspection  of  tittings,  205. 
use  of  meters  in,  203. 
Prussia,  pollution  of  streams  in,  72. 
Purification  of  water  by  freezing,  53. 
(&<?  also  Improvement.) 

QUANTITY  and  waste,  194,  206. 

necessary   for    public    supply, 
194. 

RAIN  water,  analyses  of.  48. 

as  source  of  supply,  48-55. 

requires  filtration,  175. 

storage  of,  49. 

Remsen's  investigations  at  Boston,  80,  91. 
Rhine,  suspended  matter  in,  57. 
Rhone,  suspended  matter  in,  57. 
River  Lea  water  filtered,  159,  160. 
Rivers  Pollution  Commission,  quoted,  41, 
48,  66,  74,  102,  103,  144,  145,  159,  160, 
1 66. 
Rivers  Pollution  Prevention  act  (1876),  74. 

SALRACH'S  photometer,  148. 
Samples,  collection  of,  47. 


Sand  filtration,  151. 

character  of  sand,  154. 
details  of  practice,  154. 
expense  of,  165. 
in  the  U.  S.,  161. 
principles  of,  152. 
results  of,  159. 
Saturated  solutions,  6. 
Schizomycetes,    19. 
Schiitzenberger's  oxygen  method,  31. 
Schuylkill  River,  pollution  of,  59.  . 
Sediment  in  iron  pipes,  210. 
river  waters,  57. 
Sedimentation,    147. 
Seine,  pollution  of,   59,  61. 
Self-purifying  power  of  streams,  63. 
Service  pipes,    211-215. 
Settling  basins,  146,  147- 
Sharpies,  quoted,  120. 
Sheffield,  consumption  of  water  in,  194. 
Silicated  carbon  for  filters,    172. 
Smart,  Dr.,  quoted,  49,  52,  99,  100,  130. 

simple  form  of  filter,  174. 
Smith's  process  for  coating  pipes,   208. 
Soda-water,    12,   13. 
Softening  of  hard  water,    i8r. 
Solids  in  solution,   estimation  of,  32. 

solution  of,   i. 
Solubility,  curves  of,  4. 

of  ammonia,    ir. 
carbonic  acid,    n. 
gases,   10,    II. 
liquids,  13. 
metallic  gold,  15. 
nitrogen,  n. 
solids,  i. 

sulphate  of  lime,  5. 

Solution  and  suspension  distinguished,  14. 
Solution,  i. 

chemical,  2. 

means  of  hastening,  9,  13. 
of  gases,   10. 
liquids,  13. 
solids,  I. 
physical,   i. 
Solutions,  mixed,  7. 

saturated,  6. 
supersaturated,  6. 
Solvent,  term  defined,  3. 
Spaltpilze,  19. 

Spencer's  carbide  of  iron,   159,   166. 
Sphaerozyga,  87. 
Spirillum,  -la,  20. 
Spithead,  England,  wells  at,  121. 
Splenic  fever,   cause  of,  20. 
Sponge  for  filters,    168. 
fresh-water,  80. 
growth  of  in  conduits,   207, 
Spongilla  fluviatilis,   80. 

analysis  of.  82. 
figure  of,  8 1. 
spicules  of,  81,  82. 


232 


INDEX. 


Spongy  iron  for  filters,  166,  173. 
Spree  filtered  at  Berlin,  157,  160. 
Springfield,  Mass.,  algoe  at,  90. 
Springs,   133. 

effect  of  barometric  pressure  on, 

141. 

Standards  of  purity,  40. 
St.  Louis,  artesian  well  at,  137. 

consumption  of  water  at,  195. 
settling  basins  at,  147. 
waste  of  water  at,  195. 
Storage,  effect  of,  149. 
Storer,   Prof.,  quoted,  6. 
Streams,  pollution  cf,   57. 

self-purification  of,  63. 
turbidity  of,   56. 

table,  57. 
Sulphate  of  iron  test,  35. 

lime,  solubility  of,  5. 
Sulphuretted  hydrogen  in  ponded  water, 

55. 

Supersaturated  solutions,  6,    12. 
Surface  water,  animal  and  vegetable  life 

in,  79-90. 

as  a  source  of  supply,  56. 
examination  of,  96. 

(Tables),  103,  104. 
tastes  and  odors  of,  90. 
temperature  of,  91. 
variations  of,  100. 

Suspended  matter,  determination  of,  29. 
in  Missouri  R.,  147. 
in  streams,  57. 
Suspension  defined,  14. 

TABLES  for  facilitating  calculations,  221- 

225. 

Tank  filters,  172. 
Taunton,  Mass.,  filter  gallery  at,  108. 

ground  water  near,  105. 
Temperature,  change  of  in  conduits,  207. 
means  of  measuring,  95. 
of  Fresh  Pond,  Mass.,  94. 
ground   water    supplies, 

nS. 

London  water,  93. 
surface  waters,  91. 
Thames  water  filtered,  159,  160. 
The  Hague,  water  supply  of,  121. 


Thermometers,  95. 

Tidy,  Dr.,  classification  of  waters,  42. 
Toulouse,  filter  gallery  at,  119. 
Turbidity,  estimaiion  of,  148. 

of  streams   56. 

Turbid  water,  clarification  of,  15. 
Typhoid  fever  and  drinking  water,  22. 

ULLIK,  quoted,  71. 

Unpolluted   water    from  various   sources 
(Table),   145. 

VEGETABLE  growth  on  filter  beds,  164. 
Vibrio  (-nes),  20. 

Vienna,  water  supply  of,  133,  207. 
Virginia  City,  Kev.,  conduit,  211. 
Vistula,  suspended  matter  in,  57. 
Vlissingen.     See  Flushing. 

WANKLYN,  quoted,  41. 
Wanklyn's  method  of  analysis,  38. 
Waste  of  water,  194-206. 

detection  of,  Bell's  system,  201. 

Church's  method,  202. 
Deacon's  system,  196. 

in  winter,  205. 

prevention  of,  196. 
Water  analysis,  29. 
Waters,  classification  of,  17. 
Weights    and   measures,   tables   of,   221- 

225. 
Well  at  Whiston,  Eng.,  139,  140. 

Brooklyn,  N.  Y.,  in. 
Wells,  artesian,  133. 

deep,  134,  139. 

effect  of  pumping  from,  109. 

near  salt  water,  12 1. 

pollution  of,  128. 

shallow,  1 06. 
Well  water,  examination  of,  131. 

(Table),  132, 

Whiston,  Eng.,  deep  well  at,  139,  140. 
Whitman,  T.  J.,  quoted,  195. 
Wood  charcoal  for  filters,  168,  174. 
Wooden  pipes,  211. 
Worcester,  sewage  of,  62. 
Wrrought-iron  pipes,  210. 

ZURICH,  filtration  at,  157. 
Zymotic  diseases,  18. 


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WIRE:    ITS    USE    AND    MANUFACTURE. 

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A  TREATISE  ON  CIVIL  ENGINEERING. 

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new  plates,  by  Prof.  De  Volson  Wood.  With  an  Appendix 
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AN     ELEMENTARY     COURSE      OP      CIVIL      EN- 
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MECHANICAL    PRINCIPLES    OF    ENGINEERING 
AND  ARCHITECTURE. 

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THE  THEORY  AND  PRACTICE  OF  SURVEYING. 

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versity, etc.,  etc.  Illustrated  by  upwards  of  150  engravings, 
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*  TUNNELING,     EXPLOSIVE 
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BURR. 


Giving  the  details  of  practical  Tunnel  Work,  Properties 
of  Modern  Explosives,  Principles  of  Blasting,  and  Descriptions 
and  Uses  of  the  various  Rock  Drills  and  Compressors,  together 
with  American  and  Foreign  Systems  of  Arching,  and  Tables 
showing  Costs  and  Dimensions  of  over  2,100  Tunnels  from 
every  part  of  the  World.  By  Henry  S.  Drinker.  Profiles*,  Maps, 
and  over  1,000  illustrations.  Third  edition.  4to,  half  bound,  25  00 

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it  has  been  completed  so  soon.  For  the  conception  and  execution  of  such 
a  work,  Mr.  Drinker  deserves  our  thanks  no  less  than  our  congratulations." 
— Engineering  and  Mining  Journal. 

THE    HUDSON    RIVER    TUNNEL,    SHOWING    ITS 
METHOD  OF  CONSTRUCTION, 

Carefully  collected  from  reliable  sources  and  from  the  Author's 
observations  in  the  Tunnel,  thoroughly  illustrated  by  the  draw- 
ings of  the  Engineers  in  charge.  Working  drawings  of  ail 
details,  by  S.  D.  V.  Burr.  1  vol,  4to,  containing  100  pages  and 
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important  features.  The  literary  presentation  and  the  mechanical  execu- 
tion of  the  work  are  first-class."— American  Engineer. 


EXPLOSIVE    COMPOUNDS    AND   ROCK  DRILLS. 

DKINKER.  Giving-  properties  of  Modern  Explosives,  Principles  of  Blasting:, 
and  descriptions  and  uses  of  the  various  Rock  Drills  and  Com- 
pressors, and  forming  a  SUPPLEMENTARY  VOLUME  to  the 
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THE    MODERN  HIGH  EXPLOSIVES— NITRO-GLYC- 

ERINE  AND  DYNAMITE. 

EISSLER,  Their  Manufacture,  their  Use,  and  their  Application  to  Mining 
and  Military  Engineering  ;  Pyroxyline  or  Gun  Cotton,  the  Ful- 
minates. Picrates.and  Chlorates;  also,  the  Chemistry  and  An- 
alysis of  the  Elementary  Bodies  which  enter  into  the  Manu- 
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Mining1  Engineer.  With  many  illustrative  plates.  Third 
edition 8vo,  cloth,  4  00 

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how  and  when  to  use  high  explosives  and  how  to  handle  them  safely." — 
Engineering  and  Mining  Journal. 

A    HISTORY    OF    THE    MISSISSIPPI    JETTIES    AT 
THE  MOUTH  OP  THE  MISSISSIPPI  RIVER. 

CORTHELL.  By  E,  L.  Corthell,  C.E.,  Chief  Assistant  and  Resident  Engi- 
neer during  their  construction.  Illustrated  with  portrait  of 
Captain  Eads :  24  page-plates  and  10  folding  maps.  New 
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est in  the  conquests  of  man  over  nature.'1— Journal  of  Commerce. 

WOODEN    TRESTLE    BRIDGES. 
FOSTER.  By  Wolcott  C.  Foster.  C.E. 

THE  PRACTICE  OF  THE  IMPROVEMENT  OF  THE 
NON-TIDAL  RIVERS  of  the  UJSITED  STATES. 
RUFFNER.  With  an  Examination  of  the  Results  thereof.      By  Capt.  E.  H. 

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Major  P.  C.  HAINS,  Cwps  of  Engineers,  U.S.A. 

GRAPHICS  FOR  ENGINEERS,  ARCHITECTS,  AND 

BUILDERS. 

GREENE.  A    Manual    for    Designer?,    and   a    Text-book    for    Scientific 

Schools.  TRUSSES  AND  ARCHES.  Analyzed  and  Dis- 
cussed by  Graphical  Methods  by  Chas.  E.  Greene,  Prof,  of 
Civil  Engineering,  University  of  Michigan.  In  THREE 
PARTS. 

Part    I.      ROOF    TRUSSES.      Diagrams    for    Steady   Load, 

Snow,  and  Wind.     New  revised  edition.     1890 Svo,  cloth,    1  25 

Part  II.  BRIDGE  TRUSSES.  Single,  Continuous,  and 
Draw  Spans  ;  Single  and  Multiple  Systems ;  Straight  and 
Inclined  Chords.  Third  edition <..8vo,  cloth,  2  50 

GRAPHICS  FOR  ENGINEERS,  ARCHITECTS  AND 
BUILDERS.— Continued. 

Part  III.    ARCHES  IN  WOOD,  IRON,  AND  STONE. 

For  Roofs,  Bridges,  and  Wall  Openings;  Arched  Ribs  and 
Braced  Arches ;  Stresses  from  Wind  and  Change  of  Temper- 
ature, Second  edition Svo,  cloth,  2  50 

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decidedly  recommend."— London  Engineering. 

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subject  that  has  appeared.'1 — Prof.  GEO.  L.  VOSE. 

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MECHANICS  OF  ENGINEERING. 

CHURCH.  Comprising   Statics  and    Dynamics  of  Solids,  the  Mechanics 

of  the  Materials  of  Constructions  or  Strength  and  Elasticity 
of  Beams,  Columns,  Shafts,  Arches,  etc.,  and  the  Principles  of 
Hydraulics  and  Pneumatics  with  Applications.  For  the  use  of 
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University 8vo,   cloth,  $6  00 

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a  vast  amount  of  instruction  into  a  very  small  space  without  in  any  degree 
interfering  with  the  necessary  minuteness  of  detail  or  clearness  of 
description.'1—  London  Industrial  Levitw. 

MECHANICS  OP  ENGINEER  ING- (FLUIDS). 

CHURCH.  A  Treatise  on  Hydraulics  and  Pneumatics,  for  use  in  Technical 

Schools.      By  Irving  P.    Church,   C.E  ,  'Cornell    University. 

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RETAINING  WALLS  FOR  EARTH. 

HOWE.  The   Theory  as  Developed  by  Prof.  Jacob  J.  Weyrauch,  ex- 

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STUDY  ON  RESERVOIR  WALLS. 

KRANTZ.  Translated  from  the  French  of  J.  B.  Krantz,  Engineer-in-Chief 

MAHAN.  of  Roads    and    Bridges,   by  F.  A.  Mahan.      Illustrated   with 

34  plates  comparing  Sections  of  Dams  Actually  Con  strayed 

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THE  DESIGN  AND  CONSTRUCTION  OF  MASONRY 

DAMS. 

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Quaker  Bridge  Dam.  By  £.  Wegmann,  Jr.,  Division  Engineer, 
New  Croton  Aqueduct.  Illustrated  by  types  showing  the 
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some  Dams.     Second  edition,  revised 4to,  cloth,     5  00 

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the  largest  dams  in  the  world.  The  arrangement  is  excellent,  the  text 
being  divided  into  11  chapters  and  an  appendix,  and  the  paper,  type,  and 
exterior  of  the  work  make  it  a  very  handsome  volume." — Engineering  News. 

MATERIALS  OF  CONSTRUCTION. 

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"  Materials  of  Engineering."  Treating  of  Iron  and  Steel,  their 
ores,  manufacture,  properties,  and  uses  ;  the  useful  metals  and 
their  alloys,  especially  brasses  and  bronzes,  and  the  "  kal- 
chords  ";  strength,  ductility,  resistance,  and  elasticity,  effects 
of  prolonged  and  of  repeated  loading,  crystallization  and 
granulation  ;  peculiar  metals;  Thurston's  "  maximum  alloys  "; 
stone  ;  timber  ;  preservative  processes,  etc.,  etc.  By  Prof.Robt. 
H.  Thurston,  of  Cornell  University.  Many  illustrations. 
Fourth  edition,  revised,  with  complete  Index.  .Thick  8vo,  cloth,  5  00 

"  We  think  this  volume  well  worthy  of  taking  its  place  in  the  Engineer's 
Library  as  the  '  Constructor's  Vade  Mecum.'  "—London  Engineering. 

A  TREATISE  ON  MASONRY  CONSTRUCTION. 

BAKER.  Containing  Materials  and  Method  of  Testing  Strength,  etc., 
COMBINATIONS  OF  MATERIALS  —  Composition,  etc.; 
FOUNDATIONS  — Testing  the  bearing  power  of  Soils,  etc. ; 
MASONRY  STRUCTURE— Stability  against  Sliding,  Over- 
turning, Crushing,  etc.,  etc.,  etc.  Complete  in  one  volume  of 
about  500  pages,  with  125  illustrations  and  eight  or  ten 
folding  plates.  By  Ira  O.  Baker,  C.E.  Fifth  edition,  re- 
vised  and  enlarged 8vo,  cloth,  5  00 

"If  you  wish  the  best  book  ever  published  in  the  English  language  on 
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declare  at  once  our  conviction  that  this  is  the  most  valuable  and  complete 
Treatise  on  Masonry  as  yet  published,  at  least  in  England." 

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STEREOTOMY— PROBLEMS  IN  STONE  CUTTING. 

WARREN.  In  four  classes.  1.  Plane-sided  Structures.  11.  Structures 
containing  Developable  {Surfaces.  III.  Structures  containing 
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TREATISE  ON  LEVELING  BY  VERTICAL  AN- 
GLES, 

FAUL.  And  the  Method  of  Measuring  Distances  by  Telescope  and  Rod. 
With  Tables  of  Heights  for  all  Angles,  from  zero  to  22^  <ie- 
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FIGURE  OF  THE  EARTH. 

MKRRIMAN.  An  Introduction  to  Geodesy.     By  Mansfield  Merrinian. 

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ENGLISH  AND  AMERICAN  RAILROADS  COM- 
PARED. 

DORSEY.  By  Edward  Bates  Dorsey.     With  Discussions  by  W.  W.  Evans, 

Thos.  C.  Clarke,  and  Edward  P.  North.     With  folding  plate? 

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WATER  SUPPLY. 

NICHOLS.  Considered  mainly  from  a  Chemical  and  Sanitary  standpoint. 
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HOUSE  DRAINAGE  AND  WATER  SERVICE  IN 
CITIES,  VILLAGES,  AND  RURAL  NEIGHBOR- 
HOODS. 

BAYLES.  By  Jas.   C.   Bayles.     360  pages,  illustrated  with  30  woodcuts 

and  3  folded  plates.     A  practical  work  of  value  to  the  building 
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New  edition.     8vo,  cloth,     300 

A  GUIDE  TO  SANITARY  HOUSE  INSPECTION ; 
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in    City   or   Country.       By    Wm.    P.    Gerhard,    C.E.      Third 

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COLLECTION    OF    REPORTS    (CONDENSED)     AND 
OPINIONS  OF  CHEMISTS  IN  REGARD  TO  THE 
USE  OF  LEAD  PIPE  FOR  SERVICE  PIPE 
KIRKWOOD.  In  the  Distribution  of  Water  for  the  Supply  of  Cities.     By 

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THE  WINDMILL  AS  A  PRIME  MOVER. 

WOLFF.  Comprehending  everything  of   value  relating  to   Windmills, 

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